Txoj kev loj hlob ntawm kev ua tau zoo, portable thiab miniaturized gas sensors tau txais kev saib xyuas hauv kev saib xyuas ib puag ncig, kev ruaj ntseg, kev kuaj mob thiab kev ua liaj ua teb.Ntawm cov cuab yeej tshawb nrhiav ntau yam, hlau-oxide-semiconductor (MOS) chemo-resistive gas sensors yog qhov kev xaiv nrov tshaj plaws rau kev lag luam kev lag luam vim lawv qhov ruaj khov, tsis tshua muaj nqi, thiab siab rhiab heev.Ib txoj hauv kev tseem ceeb tshaj plaws los txhim kho qhov kev ua tau zoo ntawm lub sensor yog tsim los ntawm nanosized MOS-raws li heterojunctions (hetero-nanostructured MOS) los ntawm MOS nanomaterials.Txawm li cas los xij, qhov kev hnov mob ntawm lub heteronanostructured MOS sensor txawv ntawm ib qho MOS roj sensor, vim nws nyuaj heev.Sensor kev ua tau zoo yog cuam tshuam los ntawm ntau yam tsis muaj, suav nrog lub cev thiab tshuaj lom neeg ntawm cov khoom rhiab heev (xws li cov nplej loj, qhov tsis xws luag, thiab cov khoom siv pa oxygen), kev ua haujlwm kub, thiab cov khoom siv.Qhov kev tshuaj xyuas no nthuav tawm ntau lub tswv yim los tsim kev ua haujlwm siab ntawm cov pa roj sensors los ntawm kev tshuaj xyuas cov txheej txheem kev hnov lus ntawm heterogeneous nanostructured MOS sensors.Tsis tas li ntawd, kev cuam tshuam ntawm cov qauv geometric ntawm cov cuab yeej, txiav txim siab los ntawm kev sib raug zoo ntawm cov khoom siv rhiab thiab cov electrode ua haujlwm, tau tham txog.Txhawm rau kawm txog kev coj tus cwj pwm zoo, tsab xov xwm no qhia thiab sib tham txog cov txheej txheem dav dav ntawm kev nkag siab ntawm peb cov qauv geometric ntawm cov khoom siv raws li ntau yam khoom siv heteronanostructured.Cov txheej txheem no yuav ua raws li cov lus qhia rau cov neeg nyeem yav tom ntej uas kawm txog cov txheej txheem rhiab ntawm cov pa roj carbon monoxide thiab tsim cov roj sensors ua haujlwm siab.
Cov pa phem yog qhov teeb meem loj zuj zus ntxiv thiab teeb meem loj thoob ntiaj teb ib puag ncig uas ua rau muaj kev noj qab haus huv ntawm tib neeg thiab cov tsiaj nyob.Kev nqus pa ntawm cov pa phem tuaj yeem ua rau muaj teeb meem kev noj qab haus huv ntau yam xws li kab mob ua pa, mob ntsws cancer, leukemia thiab txawm tias tuag ntxov ntxov 1,2,3,4.Los ntawm 2012 txog 2016, ntau lab tus tib neeg tau tshaj tawm tias tau tuag los ntawm huab cua phem, thiab txhua xyoo, ntau txhiab tus neeg tau raug huab cua tsis zoo5.Yog li ntawd, nws yog ib qho tseem ceeb los tsim portable thiab miniaturized gas sensors uas tuaj yeem muab cov lus pom zoo hauv lub sijhawm thiab kev tshawb pom kev ua haujlwm siab (xws li, rhiab heev, xaiv, ruaj khov, thiab cov lus teb thiab lub sijhawm rov qab).Ntxiv nrog rau kev saib xyuas ib puag ncig, roj sensors ua lub luag haujlwm tseem ceeb hauv kev nyab xeeb 6,7,8, kev kuaj mob 9,10, aquaculture11 thiab lwm qhov chaw12.
Txog rau hnub tim, ob peb lub chaw khaws roj teeb raws li cov kev txawj ntse sib txawv tau raug qhia, xws li optical13,14,20,2,22 thiab tshuaj tiv thaiv sensors 223,24.Ntawm lawv, oxide-semiconductor (Mos) Tshuaj lom zem tiv thaiv yog qhov nrov tshaj plaws hauv cov ntawv thov lag luam vim lawv qhov chaw ruaj khov thiab tus nqi qis thiab tsawg.Cov kab mob sib kis tuaj yeem txiav txim siab yooj yim los ntawm kev kuaj xyuas qhov hloov pauv hauv MOS tsis kam.Thaum ntxov 1960s, thawj chemo-resistive gas sensors raws li zno nyias cov yeeb yaj kiab tau tshaj tawm, tsim kev txaus siab rau kev kho kom tau27,28.Niaj hnub no, ntau ntau qhov sib txawv ntawm cov khoom siv roj av rhiab, thiab lawv tuaj yeem muab faib ua ob pawg raws li cov neeg nqa khoom feem ntau nrog cov qhov feem ntau them tus neeg nqa khoom.them cov cab kuj.Feem ntau, p-hom MOS tsis tshua muaj neeg nyiam tshaj li n-hom MOS vim hais tias qhov inductive teb ntawm p-hom MOS (Sp) yog proportional rau lub square root ntawm n-hom MOS (\(S_p = \sqrt { S_n}\ ) ) ntawm tib qhov kev xav (piv txwv li, tib lub qauv morphological thiab tib qhov kev hloov pauv hauv qhov khoov ntawm cov hlua hauv huab cua) 29,30.Txawm li cas los xij, ib lub hauv paus MOS sensors tseem ntsib teeb meem xws li kev tshawb nrhiav tsis txaus, tsis muaj kev nkag siab zoo thiab kev xaiv hauv kev siv tswv yim.Cov teeb meem xaiv tau tuaj yeem hais txog qee qhov los ntawm kev tsim cov arrays ntawm cov sensors (hu ua "electronic noses") thiab suav nrog kev txheeb xyuas kev txheeb xyuas xws li kev cob qhia vector quantization (LVQ), thawj feem kev tsom xam (PCA), thiab ib feem tsawg squares (PLS) tsom xam31 , 32, 33, 34, 35. Tsis tas li ntawd, kev tsim cov khoom me me MOS32, 36, 37, 38, 39 (xws li ib-dimensional (1D), 0D thiab 2D nanomaterials), nrog rau kev siv lwm yam nanomaterials ( Piv txwv li MOS40,41,42, noble hlau nanoparticles (NPs))43,44, carbon nanomaterials45,46 thiab conductive polymers47,48) los tsim nanoscale heterojunctions (ie, heteronanostructured MOS) yog lwm txoj kev nyiam los daws cov teeb meem saum toj no.Piv nrog rau cov tsoos tuab MOS zaj duab xis, qhov tsawg-seem MOS nrog rau qhov chaw siab tshwj xeeb tuaj yeem muab cov chaw ua haujlwm ntau dua rau cov pa roj adsorption thiab pab txhawb roj diffusion36,37,49.Tsis tas li ntawd, kev tsim ntawm MOS-raws li heteronanostructures tuaj yeem txuas ntxiv kev thauj khoom thauj mus los ntawm heterointerface, ua rau muaj kev hloov pauv loj hauv kev tiv thaiv vim muaj kev ua haujlwm sib txawv50,51,52.Tsis tas li ntawd, qee qhov kev cuam tshuam tshuaj lom neeg (xws li, kev ua haujlwm catalytic thiab synergistic deg tshuaj tiv thaiv) uas tshwm sim hauv kev tsim ntawm MOS heteronanostructures kuj tuaj yeem txhim kho kev ua haujlwm sensor.50,53,54 Txawm tias tsim thiab fabricating MOS heteronanostructures yuav yog ib qho kev cog lus los txhim kho. sensor kev ua tau zoo, niaj hnub chemo-resistive sensors feem ntau siv sim thiab ua yuam kev, uas yog siv sijhawm ntev thiab tsis muaj txiaj ntsig.Yog li ntawd, nws yog ib qho tseem ceeb kom nkag siab txog qhov kev hnov mob ntawm MOS raws li cov pa roj sensors vim nws tuaj yeem coj tus qauv tsim ntawm kev ua haujlwm siab kev coj ua.
Nyob rau hauv xyoo tas los no, MOS roj sensors tau tsim sai heev thiab qee cov ntawv tshaj tawm tau tshaj tawm ntawm MOS nanostructures55,56,57, chav kub kub gas sensors58,59, tshwj xeeb MOS sensor cov ntaub ntawv60,61,62 thiab tshwj xeeb roj sensors63.Ib daim ntawv tshuaj xyuas hauv Lwm Cov Kev Ntsuam Xyuas tsom mus rau elucidating lub sensing mechanism ntawm roj sensors raws li lub cev thiab tshuaj lom neeg lub cev ntawm MOS, nrog rau lub luag hauj lwm ntawm oxygen vacancies 64, lub luag hauj lwm ntawm heteronanostructures 55, 65 thiab them nqi hloov ntawm heterointerfaces 66. Ntxiv rau. , ntau lwm yam tsis zoo cuam tshuam rau kev ua haujlwm sensor, suav nrog heterostructure, grain loj, kev khiav hauj lwm kub, qhov tsis xws luag, oxygen vacancies, thiab txawm qhib siv lead ua dav hlau ntawm cov khoom rhiab heev25,67,68,69,70,71.72, 73. Txawm li cas los xij, qhov (tsis tshua muaj hais) cov qauv geometric ntawm lub cuab yeej, txiav txim siab los ntawm kev sib raug zoo ntawm cov khoom siv sensing thiab cov electrode ua haujlwm, kuj tseem cuam tshuam qhov rhiab heev ntawm lub sensor74,75,76 (saib tshooj 3 kom paub meej ntxiv) .Piv txwv li, Kumar et al.77 tau tshaj tawm ob lub pa roj sensors raws li cov khoom siv tib yam (xws li, ob txheej roj sensors raws li TiO2@NiO thiab NiO@TiO2) thiab pom cov kev hloov pauv hauv NH3 roj tsis kam vim cov cuab yeej sib txawv.Yog li ntawd, thaum txheeb xyuas cov roj-sensing mechanism, nws yog ib qho tseem ceeb uas yuav tsum tau coj mus rau hauv tus account tus qauv ntawm cov cuab yeej.Hauv kev tshuaj xyuas no, cov kws sau ntawv tsom mus rau MOS-raws li kev tshawb nrhiav mechanisms rau ntau yam heterogeneous nanostructures thiab cov khoom siv.Peb ntseeg tias qhov kev tshuaj xyuas no tuaj yeem ua cov lus qhia rau cov neeg nyeem uas xav nkag siab thiab txheeb xyuas cov cuab yeej ntsuas roj thiab tuaj yeem pab txhawb rau kev txhim kho cov kev ua haujlwm siab ntawm cov roj sensors yav tom ntej.
Ntawm daim duab.1a qhia cov qauv yooj yim ntawm lub tshuab ntsuas roj raws li ib qho MOS.Raws li qhov kub thiab txias, qhov adsorption ntawm oxygen (O2) molecules ntawm MOS nto yuav nyiam electrons los ntawm MOS thiab tsim anionic hom (xws li O2- thiab O-).Tom qab ntawd, txheej txheej electron depletion (EDL) rau ib qho n-hom MOS los yog lub qhov accumululation txheej (HAL) rau p-hom MOS yog ces tsim nyob rau saum npoo ntawm MOS 15, 23, 78. Kev sib cuam tshuam ntawm O2 thiab cov MOS ua rau cov kab hluav taws xob ntawm qhov chaw MOS khoov rau sab saud thiab tsim muaj peev xwm thaiv tau.Tom qab ntawd, thaum lub sensor raug rau lub hom phiaj roj, cov pa adsorbed rau saum npoo ntawm MOS reacts nrog ionic oxygen hom, xws li attracting electrons (oxidizing gas) los yog pub electrons (txo roj).Kev hloov hluav taws xob ntawm lub hom phiaj roj thiab MOS tuaj yeem kho qhov dav ntawm EDL lossis HAL30,81 ua rau muaj kev hloov pauv tag nrho ntawm MOS sensor.Piv txwv li, rau kev txo cov pa roj, cov hluav taws xob yuav raug xa mus los ntawm kev txo cov roj mus rau n-hom MOS, uas ua rau qis dua EDL thiab qis dua, uas yog hu ua n-hom sensor cwj pwm.Nyob rau hauv sib piv, thaum p-hom MOS raug rau ib tug txo cov roj uas txiav txim siab p-hom rhiab heev tus cwj pwm, lub HAL shrinks thiab cov kuj nce vim electron pub.Rau oxidizing gases, lub sensor teb yog rov qab rau qhov uas txo cov pa roj.
Cov txheej txheem tshawb nrhiav yooj yim rau n-hom thiab p-hom MOS rau kev txo qis thiab oxidizing gases b Cov ntsiab lus tseem ceeb thiab lub cev-tshuaj lom neeg lossis cov khoom siv koom nrog hauv semiconductor gas sensors 89
Sib nrug los ntawm cov txheej txheem tshawb pom yooj yim, cov khoom siv hluav taws xob nrhiav tau siv hauv cov khoom siv hluav taws xob siv tau zoo heev.Piv txwv li, kev siv cov roj teeb tiag tiag yuav tsum muaj ntau yam cai (xws li rhiab, xaiv tau, thiab ruaj khov) nyob ntawm cov neeg siv.Cov kev cai no muaj feem cuam tshuam nrog lub cev thiab tshuaj lom neeg ntawm cov khoom rhiab heev.Piv txwv li, Xu et al.71 qhia tau hais tias SnO2 raws li sensors ua tiav qhov siab tshaj plaws rhiab heev thaum siv lead ua txoj kab uas hla (d) yog sib npaug los yog tsawg dua ob npaug ntawm Debye ntev (λD) ntawm SnO271.Thaum d ≤ 2λD, SnO2 yog tag nrho depleted tom qab lub adsorption ntawm O2 molecules, thiab cov lus teb ntawm lub sensor rau lub txo roj yog siab tshaj.Tsis tas li ntawd, ntau yam tsis tuaj yeem cuam tshuam rau kev ua haujlwm ntawm lub sensor, suav nrog kev ua haujlwm kub, siv lead ua tsis xws luag, thiab txawm tias cov dav hlau raug siv lead ua ntawm cov khoom siv.Tshwj xeeb, qhov cuam tshuam ntawm kev ua haujlwm kub tau piav qhia los ntawm qhov muaj peev xwm sib tw ntawm tus nqi ntawm adsorption thiab desorption ntawm lub hom phiaj roj, nrog rau kev ua haujlwm saum npoo ntawm adsorbed gas molecules thiab oxygen particles4,82.Cov nyhuv ntawm crystal defects muaj feem xyuam nrog cov ntsiab lus ntawm oxygen vacancies [83, 84].Kev ua haujlwm ntawm lub sensor kuj tuaj yeem cuam tshuam los ntawm qhov sib txawv ntawm qhov qhib siv lead ua ntsej muag 67,85,86,87.Qhib cov dav hlau siv lead ua nrog qis qis qhia pom cov hlau tsis sib koom ua ke ntau dua nrog lub zog siab dua, uas txhawb nqa nto adsorption thiab reactivity88.Table 1 teev ntau yam tseem ceeb thiab lawv cov txheej txheem kev nkag siab zoo dua qub.Yog li, los ntawm kev kho cov khoom siv no, kev tshawb nrhiav kev ua tau zoo tuaj yeem txhim kho, thiab nws yog qhov tseem ceeb los txiav txim siab yam tseem ceeb cuam tshuam rau kev ua haujlwm sensor.
Yamazoe89 thiab Shimanoe li al.68,71 tau ua ib tug xov tooj ntawm cov kev tshawb fawb ntawm lub theoretical mechanism ntawm kev nkag siab ntawm sensor thiab npaj peb tus kheej yam tseem ceeb uas cuam tshuam rau sensor kev ua tau zoo, tshwj xeeb tshaj yog muaj nuj nqi receptor, transducer muaj nuj nqi, thiab utility (Fig. 1b)..Receptor muaj nuj nqi hais txog lub peev xwm ntawm MOS nto los cuam tshuam nrog cov roj molecules.Qhov kev ua haujlwm no zoo sib xws rau cov khoom siv tshuaj lom neeg ntawm MOS thiab tuaj yeem txhim kho tau zoo los ntawm kev qhia cov neeg txais kev pabcuam txawv teb chaws (piv txwv li, hlau NPs thiab lwm yam MOS).Kev ua haujlwm transducer yog hais txog lub peev xwm los hloov cov tshuaj tiv thaiv ntawm cov roj thiab MOS nto rau hauv cov teeb liab hluav taws xob uas tau tswj hwm los ntawm cov ciam teb ntawm MOS.Yog li, kev hnov mob cuam tshuam cuam tshuam los ntawm MOC qhov loj me thiab qhov ntom ntom ntawm txawv teb chaws receptors.Katoch et al.90 tau tshaj tawm tias cov qoob loo txo qis ntawm ZnO-SnO2 nanofibrils ua rau muaj ntau yam heterojunctions thiab nce sensor rhiab heev, zoo ib yam nrog transducer functionality.Wang et al.91 piv ntau qhov ntau thiab tsawg ntawm Zn2GeO4 thiab ua kom pom qhov nce ntawm 6.5 npaug ntawm qhov ntsuas qhov siab tom qab qhia cov ciam teb.Kev siv hluav taws xob yog lwm qhov tseem ceeb ntawm kev ua haujlwm zoo tshaj plaws uas piav qhia txog qhov muaj roj rau hauv MOS qauv.Yog tias cov roj molecules tsis tuaj yeem nkag mus thiab hnov mob nrog MOS sab hauv, lub sensor qhov rhiab heev yuav raug txo.Cov txiaj ntsig zoo muaj feem cuam tshuam nrog qhov tob diffusion ntawm ib qho roj, uas nyob ntawm qhov pore loj ntawm cov khoom siv.Sakai et al.92 qauv qauv ntawm cov rhiab ntawm lub sensor kom cov roj flue thiab pom tias ob lub vojvoog ntawm cov roj sensor ntawm cov pa roj diffusion qhov tob hauv lub ntsuas phoo ntawv membrane.Qhov kev sib tham saum toj no qhia tau tias cov roj txheem siab tau tuaj yeem tsim kho los ntawm kev sib npaug thiab ua haujlwm tau zoo, hloov chaw ua haujlwm, thiab cov khoom siv.
Cov haujlwm saum toj no qhia meej txog qhov kev nkag siab yooj yim ntawm ib qho MOS thiab tham txog ntau yam uas cuam tshuam rau kev ua haujlwm ntawm MOS.Ib qho ntxiv rau cov ntsiab lus no, cov roj sensors raws li heterostructures tuaj yeem txhim kho sensor kev ua tau ntxiv los ntawm kev txhim kho sensor thiab receptor.Tsis tas li ntawd, Heteronanostructures ua ntxiv mus ntxiv sensor kev ua tau zoo los ntawm kev txhim kho catalytic cov kev hloov pauv, thiab tsim ntau qhov chaw adsorption.Txog rau tam sim no, ntau cov pa roj sensors raws li MOS heteronanostructures tau kawm los tham txog cov txheej txheem rau kev txhim kho sensing95,96,97.Miller et al.55 feeb tau ntau cov tshuab uas zoo li yuav txhim kho qhov rhiab ntawm cov heteronanostructures, suav nrog cov khoom-nyob rau sab nraud, thiab tus qauv-nyob.Ntawm lawv, lub interface-delification lub tshuab ua kom zoo heev .Schottky knot).Feem ntau, MOS-raws li heteronanostructured sensors ib txwm muaj xws li ob lossis ntau dua qhov siab tshaj sensor mechanisms98,99,100.Lub synergistic nyhuv ntawm cov amplification mechanisms yuav txhim khu kev txais tos thiab ua tiav ntawm sensor signals.Yog li, nkag siab txog cov txheej txheem ntawm kev pom ntawm senseps raws li heterogeneous cov ntaub ntawv yog qhov tseem ceeb kom pab cov kws tshawb fawb muaj kev txhim kho cov roj av hauv qab cov roj ntsha tau raws li lawv cov kev xav tau.Tsis tas li ntawd, cov qauv geometric ntawm cov cuab yeej tseem tuaj yeem cuam tshuam qhov rhiab heev ntawm lub sensor 74, 75, 76. Yuav kom soj ntsuam tus cwj pwm ntawm lub sensor, qhov kev xav ntawm peb cov cuab yeej tsim raws li cov ntaub ntawv sib txawv heteronanostructured yuav raug nthuav tawm. thiab tham hauv qab no.
Nrog rau txoj kev loj hlob sai ntawm MOS raws li roj sensors, ntau yam hetero-nanostructured MOS tau raug npaj.Tus nqi hloov pauv ntawm heterointerface nyob ntawm qhov sib txawv Fermi theem (Ef) ntawm cov khoom.Nyob rau ntawm heterointerface, electrons txav los ntawm ib sab nrog ib tug loj Ef mus rau lwm sab nrog ib tug me Ef mus txog rau thaum lawv Fermi theem mus txog equilibrium, thiab qhov, vice versa.Tom qab ntawd cov cab kuj ntawm heterointerface yog depleted thiab tsim ib txheej depleted.Thaum lub sensor raug rau lub hom phiaj roj, lub heteronanostructured MOS carrier concentration hloov, raws li qhov barrier qhov siab, li no pab kom paub qhov teeb meem.Ib qho ntxiv, cov qauv sib txawv ntawm cov ntaub thaiv cov kab mob heteronanostres ua rau sib txawv ntawm cov khoom sib txawv ntawm cov ntaub ntawv thiab cov khoom sib txawv, cov kev xav sib txawv.Hauv qhov kev tshuaj xyuas no, peb nthuav tawm peb lub cuab yeej geometric thiab sib tham txog qhov kev xav ntawm txhua tus qauv.
Txawm hais tias heterojunctions ua lub luag haujlwm tseem ceeb hauv kev tshawb nrhiav roj, cov cuab yeej geometry ntawm tag nrho cov sensor tseem tuaj yeem cuam tshuam rau kev kuaj xyuas tus cwj pwm, txij li qhov chaw ntawm lub sensor conduction channel yog nyob ntawm cov cuab yeej geometry.Peb yam geometries ntawm heterojunction MOS cov cuab yeej tau tham ntawm no, raws li qhia hauv daim duab 2. Hauv thawj hom, ob qhov kev sib txuas MOS yog randomly faib ntawm ob lub electrodes, thiab qhov chaw ntawm lub conductive channel yog txiav txim los ntawm lub ntsiab MOS, qhov thib ob yog qhov tsim ntawm heterogeneous nanostructures los ntawm txawv MOS, thaum tsuas yog ib qho MOS txuas nrog electrode.electrode txuas nrog, tom qab ntawd cov channel conductive feem ntau nyob hauv MOS thiab txuas ncaj qha rau cov electrode.Hauv hom thib peb, ob cov ntaub ntawv txuas nrog ob lub electrodes sib cais, coj cov cuab yeej los ntawm ib qho heterojunction tsim ntawm ob cov ntaub ntawv.
Ib qho hyphen ntawm cov tebchaw (xws li "SnO2-NiO") qhia tias ob lub ntsiab lus tsuas yog sib xyaw (hom I).Ib qho "@" kos npe ntawm ob qhov kev sib txuas (xws li "SnO2@NiO") qhia tias cov khoom siv scaffold (NiO) yog dai kom zoo nkauj nrog SnO2 rau hom II sensor qauv.Ib txoj hlua (xws li "NiO / SnO2") qhia txog hom III sensor tsim .
Rau cov roj sensors raws li MOS composites, ob lub ntsiab lus MOS tau muab faib los ntawm cov electrodes.Ntau txoj kev tsim khoom tau tsim los npaj MOS cov khoom sib xyaw, suav nrog sol-gel, coprecipitation, hydrothermal, electrospinning, thiab mechanical mixing method98,102,103,104.Tsis ntev los no, hlau-organic moj khaum (MOFs), ib chav kawm ntawm porous crystalline cov ntaub ntawv tsim los ntawm cov chaw hlau thiab cov organic txuas, tau siv los ua cov qauv rau kev tsim cov porous MOS composites105,106,107,108.Nws yog ib qho tsim nyog sau cia tias txawm hais tias feem pua ntawm MOS cov khoom sib xyaw yog tib yam, cov yam ntxwv rhiab heev tuaj yeem sib txawv heev thaum siv cov txheej txheem tsim khoom sib txawv.109,110 Piv txwv li, Gao et al.109 fabricated ob sensors raws li MoO3 ± SnO2 composites nrog tib atomic ratio. ( Mo:Sn = 1:1.9) thiab pom tias txoj kev tsim khoom sib txawv ua rau muaj qhov sib txawv.Shaposhnik et al.110 tau tshaj tawm tias cov tshuaj tiv thaiv ntawm co-precipitated SnO2-TiO2 rau gaseous H2 txawv ntawm cov khoom sib xyaw ua ke, txawm nyob rau tib qhov sib piv Sn / Ti.Qhov sib txawv no tshwm sim vim tias kev sib raug zoo ntawm MOP thiab MOP crystallite loj sib txawv nrog cov txheej txheem sib txawv109,110.Thaum cov nplej loj thiab cov duab zoo ib yam nyob rau hauv cov nqe lus ntawm tus pub ceev thiab semiconductor hom, cov lus teb yuav tsum nyob twj ywm tib yam yog hais tias tus contact geometry tsis hloov 110.Staerz et al.111 tau tshaj tawm tias qhov kev kuaj pom tus yam ntxwv ntawm SnO2-Cr2O3 core-sheath (CSN) nanofibers thiab hauv av SnO2-Cr2O3 CSNs yog ze li qub, qhia tias nanofiber morphology tsis muaj qhov zoo dua.
Ntxiv rau txoj kev sib txawv ntawm kev tsim khoom, cov semiconductor hom ntawm ob qhov sib txawv MOSFETs kuj cuam tshuam qhov rhiab heev ntawm lub sensor.Nws tuaj yeem muab faib ua ob pawg nyob ntawm seb ob lub MOSFET yog tib hom semiconductor (nn lossis pp junction) lossis ntau hom (pn junction).Thaum cov roj sensors raws li MOS cov khoom sib xyaw ntawm tib hom, los ntawm kev hloov cov molar piv ntawm ob lub MOS, qhov rhiab heev teb cov yam ntxwv tseem tsis hloov, thiab cov sensor rhiab heev txawv nyob ntawm seb tus naj npawb ntawm nn- lossis pp-heterojunctions.Thaum ib qho kev tivthaiv muaj nyob rau hauv cov khoom sib xyaw (xws li 0.9 ZnO-0.1 SnO2 lossis 0.1 ZnO-0.9 SnO2), cov channel conduction yog txiav txim siab los ntawm MOS tseem ceeb, hu ua homojunction conduction channel 92 .Thaum qhov sib piv ntawm ob lub ntsiab lus sib piv, nws xav tias cov channel conduction yog dominated los ntawm heterojunction98,102.Yamazoe et al.112,113 tau tshaj tawm tias thaj tsam heterocontact ntawm ob lub Cheebtsam tuaj yeem txhim kho qhov rhiab heev ntawm lub sensor vim hais tias lub heterojunction barrier tsim los ntawm cov kev khiav hauj lwm sib txawv ntawm cov Cheebtsam yuav zoo tswj lub drift txav ntawm lub sensor raug electrons.Ntau yam ambient gases 112,113.Ntawm daim duab.Daim duab 3a qhia tau hais tias cov sensors raws li SnO2-ZnO fibrous hierarchical lug nrog ZnO cov ntsiab lus sib txawv (los ntawm 0 txog 10 mol% Zn) tuaj yeem xaiv ethanol.Ntawm lawv, ib lub sensor raws li SnO2-ZnO fibers (7 mol.% Zn) pom qhov siab tshaj plaws rhiab heev vim yog tsim los ntawm ib tug loj tus naj npawb ntawm heterojunctions thiab ib tug nce nyob rau hauv ib tug tshwj xeeb nto cheeb tsam, uas ua rau kom lub zog ntawm lub converter thiab txhim kho. rhiab heev 90 Txawm li cas los xij, nrog kev nce ntxiv hauv ZnO cov ntsiab lus mus rau 10 mol.%, microstructure SnO2-ZnO sib xyaw tuaj yeem qhwv thaj chaw ua kom lub ntsej muag thiab txo cov sensor rhiab heev85.Ib qho piv txwv zoo sib xws kuj tau pom rau cov sensors raws li NiO-NiFe2O4 pp heterojunction composites nrog sib txawv Fe/Ni ratios (Fig. 3b)114.
SEM dluab ntawm SnO2-ZnO fibers (7 mol.% Zn) thiab sensor teb rau ntau yam gases nrog ib tug concentration ntawm 100 ppm ntawm 260 ° C;54b Cov lus teb ntawm cov sensors raws li cov ntshiab NiO thiab NiO-NiFe2O4 composites ntawm 50 ppm ntawm ntau yam gases, 260 ° C;114 (c) Schematic daim duab ntawm tus naj npawb ntawm cov nodes nyob rau hauv xSnO2-(1-x)Co3O4 muaj pes tsawg leeg thiab cov coj kuj thiab rhiab heev tshwm sim ntawm xSnO2-(1-x)Co3O4 muaj pes tsawg leeg ib 10 ppm CO, acetone, C6H6 thiab SO2 gas ntawm 350 ° C los ntawm kev hloov cov molar piv ntawm Sn / Co 98
Pn-MOS composites qhia txawv rhiab heev tus cwj pwm nyob ntawm tus atomic ratio ntawm MOS115.Feem ntau, kev hnov mob ntawm MOS cov khoom sib xyaw yog nyob ntawm qhov uas MOS ua tus thawj coj ua rau lub sensor.Yog li ntawd, nws yog ib qho tseem ceeb heev uas yuav tsum paub qhov feem pua muaj pes tsawg leeg thiab nanostructure ntawm composites.Kim et al.98 tau lees paub qhov kev txiav txim siab no los ntawm kev sib xyaw ua ke ntawm xSnO2 ± (1-x)Co3O4 puas nanofibers los ntawm electrospinning thiab kawm txog lawv cov khoom sensor.Lawv tau pom tias tus cwj pwm ntawm SnO2-Co3O4 composite sensor hloov ntawm n-hom mus rau p-hom los ntawm kev txo cov feem pua ntawm SnO2 (Fig. 3c)98.Tsis tas li ntawd, heterojunction-dominated sensors (raws li 0.5 SnO2-0.5 Co3O4) tau pom qhov kis tau tus mob siab tshaj plaws rau C6H6 piv rau homojunction-dominant sensors (xws li, siab SnO2 lossis Co3O4 sensors).Lub hauv paus muaj siab tsis kam ntawm 0.5 SnO2-0.5 Co3O4 raws li sensor thiab nws lub peev xwm ntau dua los hloov kho tag nrho cov sensor kuj ua rau nws qhov siab tshaj plaws rau C6H6.Tsis tas li ntawd, lattice mismatch defects los ntawm SnO2-Co3O4 heterointerfaces tuaj yeem tsim qhov chaw nyiam adsorption rau cov roj molecules, yog li txhim kho cov lus teb sensor109,116.
Ntxiv nrog rau semiconductor-hom MOS, kov tus cwj pwm ntawm MOS cov khoom sib xyaw kuj tuaj yeem hloov kho siv cov chemistry ntawm MOS-117.Huo et al.117 siv ib txoj kev yooj yim soak-ci los npaj Co3O4-SnO2 composites thiab pom tias ntawm Co/Sn molar ratio ntawm 10%, lub sensor tau nthuav tawm p-type detection teb rau H2 thiab n-hom rhiab heev rau H2.teb.Sensor teb rau CO, H2S thiab NH3 gases yog qhia nyob rau hauv daim duab 4a117.Ntawm qhov qis Co/Sn piv, ntau homojunctions tsim ntawm SnO2 ± SnO2 nanograin ciam teb thiab nthuav tawm n-hom sensor teb rau H2 (Fig. 4b,c)115.Nrog rau kev nce hauv Co / Sn piv txog 10 mol.%, tsis yog SnO2-SnO2 homojunctions, ntau Co3O4-SnO2 heterojunctions tau ib txhij tsim (Fig. 4d).Txij li thaum Co3O4 tsis ua haujlwm nrog H2, thiab SnO2 reacts nrog H2, cov tshuaj tiv thaiv ntawm H2 nrog ionic oxygen hom feem ntau tshwm sim ntawm qhov chaw ntawm SnO2117.Yog li ntawd, cov hluav taws xob txav mus rau SnO2 thiab Ef SnO2 hloov mus rau cov kab hluav taws xob, thaum Ef Co3O4 tseem tsis hloov.Yog li ntawd, qhov tsis kam ntawm lub sensor nce, qhia tias cov ntaub ntawv uas muaj siab Co/Sn piv qhia p-hom sensing cwj pwm (Fig. 4e).Hauv qhov sib piv, CO, H2S, thiab NH3 gases hnov mob nrog ionic oxygen hom ntawm SnO2 thiab Co3O4 qhov chaw, thiab electrons txav los ntawm cov pa mus rau lub sensor, ua rau txo qis hauv qhov siab thiab n-hom rhiab heev (Fig. 4f)..Qhov sib txawv sensor tus cwj pwm no yog vim qhov sib txawv reactivity ntawm Co3O4 nrog cov roj sib txawv, uas tau lees paub ntxiv los ntawm Yin li al.118.Ib yam li ntawd, Katoch et al.119 tau pom tias SnO2-ZnO cov khoom sib xyaw muaj cov kev xaiv zoo thiab muaj kev nkag siab zoo rau H2.Qhov kev coj cwj pwm no tshwm sim vim H atoms tau yooj yim adsorbed rau O txoj hauj lwm ntawm ZnO vim muaj zog hybridization ntawm s-orbital ntawm H thiab p-orbital ntawm O, uas ua rau metallization ntawm ZnO120,121.
Ib co / sn-10% dynamic resistance curves rau cov roj uas muaj kev txo qis xws li H2, NH3 thiab SNO2 Composite Sensing Mechanism Diagram rau H2 thaum qis% m.Co/Sn, df Co3O4 Mechanism detection of H2 and CO, H2S and NH3 with a high Co/Sn/SnO2 composite
Yog li ntawd, peb tuaj yeem txhim kho qhov rhiab heev ntawm I-type sensor los ntawm kev xaiv cov txheej txheem tsim nyog, txo cov nplej loj ntawm cov khoom sib xyaw, thiab ua kom zoo dua cov molar piv ntawm MOS cov khoom sib xyaw.Tsis tas li ntawd, kev nkag siab tob txog chemistry ntawm cov khoom rhiab tuaj yeem txhim kho qhov kev xaiv ntawm lub sensor.
Hom II sensor qauv yog lwm qhov nrov sensor qauv uas tuaj yeem siv ntau yam khoom siv nanostructured heterogeneous, suav nrog ib qho "tus tswv" nanomaterial thiab ib qho thib ob lossis thib peb nanomaterial.Piv txwv li, ib-dimensional los yog ob-dimensional cov ntaub ntawv dai kom zoo nkauj nrog nanoparticles, core-plhaub (CS) thiab multilayer heteronanostructured cov ntaub ntawv yog feem ntau siv nyob rau hauv hom II sensor lug thiab yuav tham nyob rau hauv kom meej hauv qab no.
Rau thawj cov khoom siv heteronanostructure (decorated heteronanostructure), raws li qhia nyob rau hauv daim duab 2b(1), cov conductive raws ntawm lub sensor yog kev cob cog rua los ntawm ib lub hauv paus khoom.Vim qhov tsim ntawm heterojunctions, hloov nanoparticles tuaj yeem muab ntau qhov chaw reactive rau roj adsorption lossis desorption, thiab tseem tuaj yeem ua cov catalysts los txhim kho kev paub txog kev ua haujlwm 109,122,123,124.Yuan et al.41 tau sau tseg tias kev kho kom zoo nkauj WO3 nanowires nrog CeO2 nanodots tuaj yeem muab ntau qhov chaw adsorption ntawm CeO2@WO3 heterointerface thiab CeO2 nto thiab tsim kom muaj ntau hom chemisorbed oxygen rau cov tshuaj tiv thaiv nrog acetone.Gunawan et al.125. Ib qho ultra-high rhiab heev acetone sensor raws li ib-dimensional Au@α-Fe2O3 tau raug npaj thiab nws tau pom tias qhov rhiab heev ntawm lub sensor yog tswj los ntawm kev ua kom O2 molecules ua cov pa oxygen.Lub xub ntiag ntawm Au NPs tuaj yeem ua lub luag haujlwm txhawb kev sib cais ntawm cov pa oxygen molecules rau hauv cov pa oxygen rau oxidation ntawm acetone.Cov txiaj ntsig zoo sib xws tau txais los ntawm Choi et al.9 qhov twg Pt catalyst tau siv los cuam tshuam cov adsorbed oxygen molecules rau hauv ionized oxygen hom thiab txhim kho cov lus teb rau acetone.Nyob rau hauv 2017, tib pab neeg tshawb fawb pom tau hais tias bimetallic nanoparticles muaj ntau npaum li cas nyob rau hauv catalysis tshaj ib tug noble hlau nanoparticles, raws li qhia nyob rau hauv daim duab 5126. 5a yog ib tug schematic ntawm lub manufacturing txheej txheem rau platinum-based bimetallic (PtM) NPs siv apoferritin hlwb nrog. qhov nruab nrab qhov loj me ntawm tsawg dua 3 nm.Tom qab ntawd, siv cov txheej txheem electrospinning, PtM@WO3 nanofibers tau txais los ua kom qhov rhiab heev thiab xaiv rau acetone lossis H2S (Fig. 5b–g).Tsis ntev los no, ib qho atom catalysts (SACs) tau pom zoo catalytic kev ua tau zoo nyob rau hauv lub tshav pob ntawm catalysis thiab roj tsom xam vim lub siab tshaj plaws efficiency ntawm kev siv atoms thiab tuned hluav taws xob qauv 127,128.Shin et al.129 siv Pt-SA anchored carbon nitride (MCN), SnCl2 thiab PVP nanosheets ua tshuaj los npaj Pt@MCN@SnO2 inline fibers rau kev kuaj roj.Txawm hais tias muaj cov ntsiab lus tsawg heev ntawm Pt@MCN (los ntawm 0.13 wt.% mus rau 0.68 wt.%), kev tshawb nrhiav kev ua haujlwm ntawm cov pa roj formaldehyde Pt@MCN@SnO2 zoo dua rau lwm cov qauv siv (ntshiab SnO2, MCN@SnO2 thiab Pt NPs@ NPO 2)..Qhov kev tshawb pom zoo tshaj plaws no tuaj yeem raug ntaus nqi rau qhov siab tshaj plaws atomic efficiency ntawm Pt SA catalyst thiab qhov tsawg kawg nkaus ntawm SnO2129 active sites.
Apoferritin-loaded encapsulation txoj kev kom tau txais PtM-apo (PtPd, PtRh, PtNi) nanoparticles;dynamic gas rhiab heev ntawm bd pristine WO3, PtPd@WO3, PtRn@WO3, thiab Pt-NiO@WO3 nanofibers;Raws li, piv txwv li, ntawm cov khoom xaiv ntawm PtPd@WO3, PtRn@WO3 thiab Pt-NiO@WO3 nanofiber sensors rau 1 ppm ntawm interfering gas 126
Tsis tas li ntawd, heterojunctions tsim los ntawm cov ntaub ntawv scaffold thiab nanoparticles kuj tuaj yeem hloov kho cov kev coj ua tau zoo los ntawm kev hloov kho radial los txhim kho kev ua haujlwm ntawm lub sensor130,131,132.Ntawm daim duab.Daim duab 6a qhia txog cov yam ntxwv sensor ntawm ntshiab SnO2 thiab Cr2O3 @ SnO2 nanowires rau txo thiab oxidizing gases thiab cov khoom siv sensor mechanisms131.Piv rau cov ntshiab SnO2 nanowires, cov lus teb ntawm Cr2O3 @ SnO2 nanowires kom txo tau cov pa roj tau zoo heev, thaum cov lus teb rau oxidizing gases yog phem.Cov phenomena no yog ze ze rau lub zos deceleration ntawm cov conduction raws ntawm SnO2 nanowires nyob rau hauv lub radial kev taw qhia ntawm lub tsim pn heterojunction.Lub sensor kuj tuaj yeem hloov kho yooj yim los ntawm kev hloov EDL dav ntawm qhov chaw ntawm ntshiab SnO2 nanowires tom qab raug txo qis thiab oxidizing gases.Txawm li cas los xij, rau Cr2O3 @ SnO2 nanowires, thawj DEL ntawm SnO2 nanowires nyob rau hauv huab cua yog nce piv rau cov ntshiab SnO2 nanowires, thiab cov conduction channel yog suppressed vim yog tsim ntawm heterojunction.Yog li ntawd, thaum lub sensor raug rau ib tug txo cov pa roj, cov ntxiab electrons raug tso tawm rau hauv SnO2 nanowires thiab EDL yog drastic txo, uas ua rau rhiab heev dua li ntshiab SnO2 nanowires.Hloov pauv, thaum hloov mus rau cov roj oxidizing, DEL nthuav dav yog txwv, ua rau tsis tshua muaj siab.Cov txiaj ntsig zoo sib xws tau pom los ntawm Choi li al., 133 uas SnO2 nanowires dai kom zoo nkauj nrog p-hom WO3 nanoparticles pom tau tias muaj txiaj ntsig zoo dua los txo cov pa roj, thaum n-decorated SnO2 sensors tau txhim kho rhiab heev rau oxidizing gases.TiO2 nanoparticles (Fig. 6b) 133. Qhov tshwm sim no feem ntau yog vim kev ua haujlwm sib txawv ntawm SnO2 thiab MOS (TiO2 lossis WO3) nanoparticles.Nyob rau hauv p-hom (n-hom) nanoparticles, kev ua haujlwm ntawm cov khoom siv hauv lub moj khaum (SnO2) nthuav dav (lossis cog lus) hauv cov kev taw qhia radial, thiab tom qab ntawd, nyob rau hauv qhov kev txiav txim ntawm kev txo qis (lossis oxidation), txuas ntxiv (lossis luv) ntawm cov conduction channel ntawm SnO2 - tav) ntawm cov roj (Fig. 6b).
Radial modulation mechanism tshwm sim los ntawm kev hloov kho LF MOS.Cov ntsiab lus ntawm cov lus teb roj rau 10 ppm txo thiab oxidizing gases raws li cov ntshiab SnO2 thiab Cr2O3 @ SnO2 nanowires thiab sib thooj sensing mechanism schematic daim duab;thiab sib thooj schemes ntawm WO3 @ SnO2 nanorods thiab nrhiav kom tau mechanism133
Nyob rau hauv bilayer thiab multilayer heterostructure pab kiag li lawm, conduction channel ntawm cov cuab yeej yog dominated los ntawm txheej (feem ntau yog lub hauv qab txheej) nyob rau hauv kev sib cuag ncaj qha nrog cov electrodes, thiab lub heterojunction tsim nyob rau hauv lub interface ntawm ob txheej muaj peev xwm tswj cov conductivity ntawm lub hauv qab txheej. .Yog li ntawd, thaum gases cuam tshuam nrog cov txheej saum toj kawg nkaus, lawv tuaj yeem cuam tshuam rau cov kev sib txuas ntawm cov txheej hauv qab thiab qhov tsis kam 134 ntawm cov cuab yeej.Piv txwv li, Kumar et al.77 qhia txog tus cwj pwm txawv ntawm TiO2@NiO thiab NiO@TiO2 ob txheej txheej rau NH3.Qhov sib txawv no tshwm sim vim hais tias cov conduction raws ntawm ob lub sensors nyob rau hauv cov khaubncaws sab nraud povtseg ntawm cov ntaub ntawv sib txawv (NiO thiab TiO2, raws li), thiab ces cov variations nyob rau hauv lub hauv paus conduction raws yog txawv77.
Bilayer lossis multilayer heteronanostructures feem ntau yog tsim los ntawm sputtering, atomic txheej deposition (ALD) thiab centrifugation56,70,134,135,136.Cov yeeb yaj kiab tuab thiab qhov chaw sib cuag ntawm ob cov ntaub ntawv tuaj yeem tswj tau zoo.Cov duab 7a thiab b qhia NiO@SnO2 thiab Ga2O3@WO3 nanofilms tau los ntawm sputtering rau ethanol detection135,137.Txawm li cas los xij, cov txheej txheem no feem ntau tsim cov yeeb yaj kiab tiaj tus, thiab cov yeeb yaj kiab tiaj tiaj no tsis tshua muaj siab dua li 3D nanostructured cov ntaub ntawv vim lawv qhov chaw tshwj xeeb thiab cov pa permeability.Yog li ntawd, lub tswv yim ua kua-theem rau fabricating bilayer films nrog cov hierarchies sib txawv kuj tau raug npaj los txhim kho perceptual kev ua tau zoo los ntawm kev ua kom cov cheeb tsam tshwj xeeb 41,52,138.Zhu et al139 ua ke sputtering thiab hydrothermal cov tswv yim los tsim ZnO nanowires heev tshaj SnO2 nanowires (ZnO@SnO2 nanowires) rau H2S nrhiav tau (Fig. 7c).Nws cov lus teb rau 1 ppm H2S yog 1.6 npaug siab dua li ntawm lub sensor raws li sputtered ZnO@SnO2 nanofilms.Liu et al.52 qhia txog kev ua haujlwm siab H2S sensor siv ob-kauj ruam hauv situ tshuaj deposition txoj kev los fabricate hierarchical SnO2@NiO nanostructures ua raws li thermal annealing (Daim duab 10d).Piv rau cov pa sputtered SnO2@NiO bilayer films, rhiab heev kev ua tau zoo ntawm SnO2@NiO hierarchical bilayer qauv yog ho txhim khu kev qha vim qhov nce nyob rau hauv tej thaj chaw saum npoo 52,137.
Ob chav txheej roj sensor raws li MOS.NiO@SnO2 nanofilm rau ethanol nrhiav pom;137b Ga2O3 @ WO3 nanofilm rau ethanol nrhiav pom;135c tau txiav txim siab heev SnO2@ZnO bilayer hierarchical qauv rau H2S nrhiav pom;139d SnO2 @ NiO bilayer hierarchical qauv rau kev kuaj H2S52.
Nyob rau hauv hom II li raws li cov tub ntxhais-plhaub heteronanostructures (CSHNs), lub sensing mechanism yog complex, vim hais tias cov conduction raws tsis txwv rau lub puab plhaub.Ob txoj kev tsim khoom thiab cov tuab (hs) ntawm pob tuaj yeem txiav txim siab qhov chaw ntawm cov khoom siv hluav taws xob.Piv txwv li, thaum siv cov txheej txheem hauv qab-up synthesis, conduction channel feem ntau yog txwv rau cov tub ntxhais sab hauv, uas zoo ib yam hauv cov qauv rau ob-txheej lossis ntau txheej txheej txheej (Fig. 2b(3)) 123, 140, 141, 142, 143. Xu et al.144 tau tshaj tawm txoj hauv kev hauv qab kom tau txais CSHN NiO @ α-Fe2O3 thiab CuO @ α-Fe2O3 los ntawm kev tso ib txheej ntawm NiO lossis CuO NPs ntawm α-Fe2O3 nanorods uas cov channel conduction raug txwv los ntawm lub hauv paus.(nanorods α-Fe2O3).Liu et al.142 kuj tau ua tiav hauv kev txwv txoj kev coj mus rau qhov tseem ceeb ntawm CSHN TiO2 @ Si los ntawm kev tso TiO2 ntawm kev npaj arrays ntawm silicon nanowires.Yog li ntawd, nws tus cwj pwm sensing (p-hom lossis n-hom) tsuas yog nyob ntawm hom semiconductor ntawm silicon nanowire.
Txawm li cas los xij, feem ntau tshaj tawm CSHN-raws li sensors (Daim duab 2b(4)) tau tsim los ntawm kev hloov cov hmoov ntawm cov khoom siv CS synthesized mus rau chips.Nyob rau hauv cov ntaub ntawv no, txoj kev conduction ntawm lub sensor yog cuam tshuam los ntawm lub tsev thickness (hs).Kim pab pawg tau tshawb xyuas cov txiaj ntsig ntawm hs ntawm kev ua haujlwm ntawm cov pa roj thiab tau thov kom muaj peev xwm nrhiav tau cov tshuab 100,112,145,146,147,148. Nws ntseeg tau tias ob yam ua rau muaj kev nkag siab ntawm cov qauv no: (1) radial modulation ntawm EDL ntawm lub plhaub thiab (2) hluav taws xob teb smearing nyhuv (Fig. 8) 145. Cov kws tshawb fawb tau hais tias cov conduction channel ntawm cov cab kuj feem ntau yog nyob rau hauv lub plhaub txheej thaum hs > λD ntawm lub plhaub txheej 145. Nws ntseeg tau tias ob yam ua rau muaj kev nkag siab ntawm cov qauv no: (1) radial modulation ntawm EDL ntawm lub plhaub thiab (2) hluav taws xob teb smearing nyhuv (Fig. 8) 145. Cov kws tshawb fawb tau hais tias cov conduction channel ntawm cov cab kuj feem ntau yog nyob rau hauv lub plhaub txheej thaum hs > λD ntawm lub plhaub txheej 145. Считается, что в механизме восприятия этой структуры участвуют два фактора: (1) радиальная модуляция ДЭС оболочки и (2) эффект размытия электрического поля (рис. 8) 145. Исследователи отметили, что канал проводимости носителей в основном приурочено к оболочке, когда hs > dlD оболочки 145. Nws ntseeg tau tias ob yam kev koom tes muaj kev koom tes hauv lub tshuab ntawm kev pom ntawm cov qauv no: (1) cov nyhuv radial hluav taws xob (Daim duab 8) 145. Cov kws tshawb nrhiav tau sau tseg tias cov cab kuj conduction channel yog tsuas yog nyob rau hauv lub plhaub thaum hs > λD shells145.Nws ntseeg tau tias muaj ob yam ua rau cov qauv kuaj pom no ntawm cov plhaub thiab (2) cov nyhuv ntawm hluav taws xob teb smearing (Daim duab 8) 145.研究人员提到传导通道当壳层的hs > λD145时，载流子的数量主要局限于壳层. > λD145 时，载流子的数量主要局限于壳层. Исследователи отметили, что канал проводимости Когда hs > λD145 оболочки, количество носителей в оснионовном Cov kws tshawb fawb tau sau tseg tias cov channel conduction Thaum hs > λD145 ntawm lub plhaub, cov neeg nqa khoom feem ntau tsuas yog txwv los ntawm lub plhaub.Yog li ntawd, nyob rau hauv lub resistive modulation ntawm lub sensor raws li CSHN, lub radial modulation ntawm lub cladding DEL prevails (Fig. 8a).Txawm li cas los xij, ntawm hs ≤ λD ntawm lub plhaub, cov pa oxygen adsorbed los ntawm lub plhaub thiab cov heterojunction tsim ntawm CS heterojunction yog tag nrho ntawm electrons. Yog li ntawd, lub conduction channel tsis yog tsuas yog nyob rau hauv lub plhaub txheej tab sis kuj yog ib feem nyob rau hauv lub core ib feem, tshwj xeeb tshaj yog thaum hs < λD ntawm lub plhaub txheej. Yog li ntawd, lub conduction channel tsis yog tsuas yog nyob rau hauv lub plhaub txheej tab sis kuj yog ib feem nyob rau hauv lub core ib feem, tshwj xeeb tshaj yog thaum hs < λD ntawm lub plhaub txheej. Поэтому канал проводимости располагается не только внутри оболочечного слоя, но и частично в сердцевинной части, особенно при hs < λD оболочечного слоя. Yog li ntawd, lub conduction channel nyob tsis tau tsuas yog nyob rau hauv lub plhaub txheej, tab sis kuj ib feem nyob rau hauv lub core ib feem, tshwj xeeb tshaj yog nyob rau hauv hs < λD ntawm lub plhaub txheej.因此，传导通道不仅位于壳层内部，而且部分位于芯部，尤其是当壳层的hs < λD 时. hs <λD 时. Поэтому канал проводимости располагается не только внутри оболочки, но и частично в сердцевине, ос. Yog li ntawd, lub conduction channel nyob tsis tau tsuas yog nyob rau hauv lub plhaub, tab sis kuj ib feem nyob rau hauv lub tub ntxhais, tshwj xeeb tshaj yog nyob rau hauv hs < λD ntawm lub plhaub.Nyob rau hauv cov ntaub ntawv no, ob qho tag nrho depleted electron plhaub thiab ib feem depleted core txheej pab modulate tsis kam ntawm tag nrho CSHN, uas ua rau ib tug hluav taws xob teb tail effect (Fig. 8b).Qee lwm cov kev tshawb fawb tau siv EDL ntim feem ntau lub tswv yim es tsis txhob siv hluav taws xob hluav taws xob los ntsuas qhov hs effect100,148.Muab ob qho kev koom tes no rau hauv tus account, tag nrho cov kev hloov pauv ntawm CSHN tsis kam mus txog nws qhov txiaj ntsig zoo tshaj plaws thaum hs piv rau cov sheath λD, raws li qhia hauv daim duab 8c.Yog li, qhov zoo tshaj plaws hs rau CSHN tuaj yeem nyob ze ntawm lub plhaub λD, uas yog raws li kev soj ntsuam kev soj ntsuam99,144,145,146,149.Ntau qhov kev tshawb fawb tau pom tias hs tuaj yeem cuam tshuam qhov rhiab heev ntawm CSHN-raws li pn-heterojunction sensors40,148.Li et al.148 and Bai et al.40 systematically soj ntsuam cov nyhuv ntawm hs ntawm kev ua tau zoo ntawm pn-heterojunction CSHN sensors, xws li TiO2@CuO thiab ZnO@NiO, los ntawm kev hloov lub cladding ALD voj voog.Raws li qhov tshwm sim, qhov kev xav tau hloov pauv ntawm p-hom mus rau n-hom nrog nce hs40,148.Qhov kev coj cwj pwm no yog vim qhov tseeb tias thaum xub thawj (nrog rau tsawg tus lej ntawm ALD cycles) heterostructures tuaj yeem suav tias yog hloov kho heteronanostructures.Yog li, qhov kev coj ua channel raug txwv los ntawm cov txheej txheem tseem ceeb (p-hom MOSFET), thiab lub sensor pom tus cwj pwm p-hom nrhiav kom pom.Raws li tus naj npawb ntawm ALD cycles nce, lub cladding txheej (n-hom MOSFET) ua quasi-nruam thiab ua raws li ib tug conduction channel, ua rau n-hom rhiab heev.Cov cwj pwm hloov pauv zoo sib xws tau tshaj tawm rau pn branched heteronanostructures 150,151 .Zhou et al.150 tshawb xyuas qhov rhiab heev ntawm Zn2SnO4 @ Mn3O4 ceg heteronanostructures los ntawm kev tswj cov Zn2SnO4 cov ntsiab lus nyob rau saum npoo ntawm Mn3O4 nanowires.Thaum Zn2SnO4 nuclei tsim ntawm Mn3O4 nto, p-hom rhiab heev tau pom.Nrog rau kev nce ntxiv hauv Zn2SnO4 cov ntsiab lus, lub sensor raws li branched Zn2SnO4 @ Mn3O4 heteronanostructures hloov mus rau n-hom sensor cwj pwm.
Cov lus piav qhia ntawm lub tswv yim ntawm ob lub luag haujlwm sensor mechanism ntawm CS nanowires tau qhia.Ib qho kev hloov pauv tsis zoo vim qhov kev hloov pauv radial ntawm cov khoom siv hluav taws xob tsis zoo, b Cov nyhuv tsis zoo ntawm smearing ntawm kev hloov pauv tsis kam, thiab c Tag nrho cov kev hloov kho ntawm CS nanowires vim yog kev sib xyaw ntawm ob qho tib si cuam tshuam 40
Hauv kev xaus, hom II sensors suav nrog ntau qhov sib txawv hierarchical nanostructures, thiab sensor kev ua tau zoo yog nyob ntawm qhov kev npaj ntawm cov kab hluav taws xob.Yog li ntawd, nws yog ib qho tseem ceeb los tswj txoj hauj lwm ntawm cov conduction channel ntawm lub sensor thiab siv ib tug haum heteronanostructured MOS qauv los kawm txog lub ncua kev sensing mechanism ntawm hom II sensors.
Hom III sensor qauv tsis yog ntau heev, thiab cov conduction channel yog raws li ib tug heterojunction tsim ntawm ob semiconductors txuas nrog ob electrodes, feem.Cov qauv cuab yeej tshwj xeeb feem ntau tau txais los ntawm cov txheej txheem micromachining thiab lawv cov txheej txheem kev hnov lus txawv heev ntawm ob lub qauv sensor dhau los.IV nkhaus ntawm hom III sensor feem ntau nthuav tawm cov yam ntxwv kho kom zoo vim yog heterojunction tsim48,152,153.I-V tus yam ntxwv nkhaus ntawm qhov zoo tshaj plaws heterojunction tuaj yeem piav qhia los ntawm lub thermionic mechanism ntawm electron emission tshaj qhov siab ntawm heterojunction barrier152,154,155.
qhov twg Va yog qhov tsis ncaj ncees lawm, A yog qhov chaw ntaus ntawv, k yog Boltzmann tas li, T yog qhov kub thiab txias, q yog tus cab kuj, Jn thiab Jp yog lub qhov thiab electron diffusion tam sim no ntom, feem.IS sawv cev rau qhov rov qab saturation tam sim no, txhais tau tias: 152,154,155
Yog li ntawd, tag nrho cov tam sim no ntawm pn heterojunction nyob ntawm qhov kev hloov pauv ntawm qhov concentration ntawm cov cab kuj thiab qhov kev hloov ntawm qhov siab ntawm qhov barrier ntawm heterojunction, raws li qhia hauv kab zauv (3) thiab (4) 156.
qhov twg nn0 thiab pp0 yog qhov concentration ntawm electrons (qhov) hauv n-hom (p-type) MOS, \(V_{bi}^0\) yog qhov muaj peev xwm ua tau, Dp (Dn) yog qhov sib txawv ntawm qhov sib txawv. electrons (qhov), Ln (Lp) yog qhov ntev diffusion ntawm electrons (qhov), ΔEv (ΔEc) yog lub zog hloov ntawm valence band (conduction band) ntawm heterojunction.Txawm hais tias qhov ceev tam sim no yog proportional rau cov cab kuj ceev, nws yog exponentially inversely proportional rau \(V_{bi}^0\).Yog li ntawd, tag nrho cov kev hloov nyob rau hauv tam sim no ceev ceev nyob rau hauv lub modulation ntawm qhov siab ntawm heterojunction barrier.
Raws li tau hais los saum no, kev tsim cov hetero-nanostructured mostets (piv txwv li, hom i thiab hom II khoom), ntau dua li ib tus neeg.Thiab rau hom III cov khoom siv, cov lus teb heteronanostructure tuaj yeem siab dua ob yam khoom siv 48,153 lossis siab dua ib qho khoom siv 76, nyob ntawm seb cov khoom siv tshuaj lom neeg.Ob peb daim ntawv qhia tau pom tias cov lus teb ntawm heteronanostructures yog ntau dua li ntawm ib qho kev tivthaiv thaum ib qho ntawm cov khoom tsis zoo rau lub hom phiaj gas48,75,76,153.Hauv qhov no, lub hom phiaj roj yuav cuam tshuam nrog cov txheej txheem rhiab thiab ua rau hloov Ef ntawm cov txheej txheem rhiab heev thiab kev hloov pauv ntawm qhov siab ntawm heterojunction barrier.Tom qab ntawd tag nrho cov tam sim no ntawm cov cuab yeej yuav hloov pauv loj, vim nws cuam tshuam nrog qhov siab ntawm heterojunction barrier raws li qhov sib npaug.(3) thiab (4) 48,76,153.Txawm li cas los xij, thaum ob qho tib si n-hom thiab p-hom Cheebtsam yog rhiab rau lub hom phiaj roj, kev tshawb nrhiav kev ua tau zoo tuaj yeem nyob ntawm qhov chaw.José et al.76 tau tsim ib qho ntxeem tau NiO / SnO2 zaj duab xis NO2 sensor los ntawm sputtering thiab pom tias lub sensor rhiab heev tsuas yog siab dua li ntawm NiO raws li sensor, tab sis qis dua li ntawm SnO2 raws li sensor.sensor.Qhov tshwm sim no yog vim qhov tseeb tias SnO2 thiab NiO nthuav tawm cov kev cuam tshuam rov qab rau NO276.Tsis tas li ntawd, vim hais tias ob lub ntsiab lus muaj qhov sib txawv ntawm cov pa rhiab heev, lawv tuaj yeem muaj tib txoj kev xav pom oxidizing thiab txo cov pa roj.Piv txwv li, Kwon et al.157 tau thov kom muaj NiO/SnO2 pn-heterojunction gas sensor los ntawm oblique sputtering, raws li qhia hauv daim duab 9a.Interestingly, lub NiO/SnO2 pn-heterojunction sensor qhia tib rhiab heev rau H2 thiab NO2 (Fig. 9a).Txhawm rau daws qhov tshwm sim no, Kwon et al.157 tau soj ntsuam xyuas seb NO2 thiab H2 hloov pauv cov neeg nqa khoom ntau npaum li cas thiab tuned \(V_{bi}^0\) ntawm ob qho khoom siv IV-tus yam ntxwv thiab kev sim hauv computer (Fig. 9bd).Daim duab 9b thiab c qhia lub peev xwm ntawm H2 thiab NO2 los hloov cov cab kuj ceev ntawm cov sensors raws li p-NiO (pp0) thiab n-SnO2 (nn0), feem.Lawv tau pom tias pp0 ntawm p-hom NiO hloov me ntsis hauv NO2 ib puag ncig, thaum nws hloov pauv ntau hauv H2 ib puag ncig (Fig. 9b).Txawm li cas los xij, rau n-hom SnO2, nn0 coj tus cwj pwm tsis zoo (Daim duab 9c).Raws li cov txiaj ntsig no, cov kws sau ntawv xaus lus tias thaum H2 tau siv rau lub sensor raws li NiO / SnO2 pn heterojunction, qhov nce hauv nn0 ua rau muaj kev nce hauv Jn, thiab \(V_{bi}^0\) ua rau muaj txo cov lus teb (Fig. 9d ).Tom qab raug NO2, ob qho tib si qhov txo qis hauv nn0 hauv SnO2 thiab qhov nce me me hauv pp0 hauv NiO ua rau muaj qhov txo qis hauv \(V_{bi}^0\), uas ua kom muaj kev nce siab hauv cov lus teb (Daim duab 9d. ) 157 Nyob rau hauv xaus, cov kev hloov nyob rau hauv lub concentration ntawm cov cab kuj thiab \(V_{bi}^0\) ua rau cov kev hloov nyob rau hauv tag nrho cov tam sim no, uas ntxiv cuam tshuam lub peev xwm nrhiav tau.
Lub tshuab nqus tsev ntawm cov roj sensor yog raws li cov qauv ntawm hom III ntaus ntawv.Scanning electron microscopy (SEM) cross-sectional dluab, p-NiO/n-SnO2 nanocoil device thiab sensor zog ntawm p-NiO/n-SnO2 nanocoil heterojunction sensor ntawm 200 ° C rau H2 thiab NO2;b, cross-sectional SEM ntawm c-device, thiab simulation tshwm sim ntawm ib lub cuab yeej nrog p-NiO b-txheej thiab n-SnO2 c-txheej.b p-NiO sensor thiab c n-SnO2 sensor ntsuas thiab phim cov yam ntxwv I-V hauv huab cua qhuav thiab tom qab raug H2 thiab NO2.Daim ntawv qhia ob-dimensional ntawm b-qhov ceev hauv p-NiO thiab daim ntawv qhia ntawm c-electrons hauv n-SnO2 txheej nrog cov xim nplai tau ua qauv siv Sentaurus TCAD software.d Simulation cov txiaj ntsig qhia 3D daim ntawv qhia p-NiO / n-SnO2 hauv huab cua qhuav, H2 thiab NO2157 hauv ib puag ncig.
Ntxiv nrog rau cov khoom siv tshuaj lom neeg ntawm cov khoom siv nws tus kheej, cov qauv ntawm Hom III ntaus ntawv qhia tau tias muaj peev xwm tsim cov khoom siv hluav taws xob rau tus kheej, uas tsis tuaj yeem ua tau nrog Hom I thiab Hom II.Vim tias lawv qhov chaw hluav taws xob muaj hluav taws xob (BEF), pn heterojunction diode cov qauv feem ntau yog siv los tsim cov khoom siv hluav taws xob photovoltaic thiab qhia tau tias muaj peev xwm ua rau nws tus kheej-powered photoelectric gas sensors ntawm chav tsev kub hauv qab illumination74,158,159,160,161.BEF ntawm lub heterointerface, tshwm sim los ntawm qhov sib txawv ntawm Fermi qib ntawm cov ntaub ntawv, kuj ua rau muaj kev sib cais ntawm electron-qhov khub.Qhov kom zoo dua ntawm tus kheej-powered photovoltaic gas sensor yog nws lub zog siv tsawg vim nws tuaj yeem nqus lub zog ntawm lub teeb pom kev zoo thiab tom qab ntawd tswj nws tus kheej lossis lwm yam khoom siv me me yam tsis tas yuav muaj lub zog sab nraud.Piv txwv li, Tanuma thiab Sugiyama162 tau tsim NiO / ZnO pn heterojunctions ua lub hnub ci hlwb kom qhib SnO2-based polycrystalline CO2 sensors.Gad et al.74 qhia txog tus kheej-powered photovoltaic roj sensor raws li Si/ZnO@CdS pn heterojunction, raws li qhia hauv daim duab 10a.Vertically oriented ZnO nanowires tau cog ncaj qha rau ntawm p-hom silicon substrates los ua Si / ZnO pn heterojunctions.Tom qab ntawd CdS nanoparticles tau hloov kho rau ntawm ZnO nanowires los ntawm kev hloov kho tshuaj lom neeg.Ntawm daim duab.10a qhia tawm cov kab Si / ZnO @ CdS cov lus teb rau O2 thiab ethanol.Nyob rau hauv illumination, qhov qhib-circuit voltage (Voc) vim kev sib cais ntawm electron-qhov khub thaum lub sij hawm BEP ntawm lub Si / ZnO heterointerface nce linearly nrog cov xov tooj ntawm kev cob cog rua diodes74,161.Voc tuaj yeem sawv cev los ntawm kev sib npaug.(5) 156,
qhov twg ND, NA, thiab Ni yog qhov sib xyaw ntawm cov neeg pub dawb, cov neeg txais, thiab cov khoom siv sab hauv, feem, thiab k, T, thiab q yog tib yam tsis zoo ib yam li hauv kab zauv dhau los.Thaum raug oxidizing gases, lawv rho tawm electrons los ntawm ZnO nanowires, uas ua rau ib tug txo nyob rau hauv \(N_D^{ZnO}\) thiab Voc.Hloov pauv, txo cov roj ua rau muaj kev nce hauv Voc (Fig. 10a).Thaum kho ZnO nrog CdS nanoparticles, photoexcited electrons nyob rau hauv CdS nanoparticles yog txhaj rau hauv lub conduction band ntawm ZnO thiab cuam tshuam nrog cov roj adsorbed, yog li ua rau kev nkag siab efficiency 74,160.Ib tug zoo xws li tus kheej-powered photovoltaic roj sensor raws li Si / ZnO tau tshaj tawm los ntawm Hoffmann li al.160, 161 (Fig. 10b).Qhov no sensor tuaj yeem npaj tau siv kab ntawm amine-ua haujlwm zoo-sam) thiab thiol ((3-mercaptoproyl) -functionalized, kom kho txoj haujlwm ua haujlwm ntawm lub hom phiaj roj rau kev xaiv nrhiav tau ntawm NO2 (trimethoxysilane) (thiol-functionalized-SAM)) (Fig. 10b) 74,161.
Tus kheej-powered photoelectric gas sensor raws li tus qauv ntawm hom III ntaus ntawv.Tus kheej-powered photovoltaic gas sensor raws li Si / ZnO @ CdS, nws tus kheej-powered sensing mechanism thiab sensor teb rau oxidized (O2) thiab txo (1000 ppm ethanol) gases nyob rau hauv tshav ntuj;74b Self-powered photovoltaic gas sensor raws li Si ZnO / ZnO sensors thiab sensors teb rau ntau yam gases tom qab functionalization ntawm ZnO SAM nrog terminal amines thiab thiols 161
Yog li ntawd, thaum sib tham txog lub rhiab mechanism ntawm hom III sensors, nws yog ib qho tseem ceeb los txiav txim qhov kev hloov nyob rau hauv qhov siab ntawm lub heterojunction barrier thiab lub peev xwm ntawm cov roj los cuam tshuam cov carrier concentration.Tsis tas li ntawd, illumination tuaj yeem tsim cov neeg nqa khoom photogenerated uas hnov mob nrog cov pa roj, uas tau cog lus rau tus kheej-powered gas detection.
Raws li tau tham hauv cov ntaub ntawv tshuaj xyuas no, ntau qhov sib txawv MOS heteronanostructures tau raug tsim los txhim kho kev ua haujlwm sensor.Lub Vev Xaib ntawm Kev Tshawb Fawb Kev Tshawb Fawb tau tshawb nrhiav ntau cov ntsiab lus (hlau oxide composites, core-sheath hlau oxides, txheej hlau oxides, thiab nws tus kheej-powered gas analyzers) nrog rau cov yam ntxwv txawv (kev nplua nuj, rhiab heev / xaiv, lub zog tsim muaj peev xwm, kev tsim khoom) .Txoj Kev Cov yam ntxwv ntawm peb ntawm peb cov khoom siv no tau qhia hauv Table 2. Lub tswv yim tsim tag nrho rau kev ua haujlwm siab ntawm cov roj sensors tau tham los ntawm kev tshuaj xyuas peb yam tseem ceeb uas tau hais los ntawm Yamazoe.Mechanisms rau MOS Heterostructure Sensors Kom nkag siab txog cov yam ntxwv cuam tshuam rau cov roj sensors, ntau yam MOS tsis (xws li, grain loj, kev khiav hauj lwm kub, tsis xws luag thiab oxygen vacancy density, qhib siv lead ua dav hlau) tau ua tib zoo kawm.Cov qauv ntaus ntawv, uas tseem yog ib qho tseem ceeb rau lub sensor tus cwj pwm sensing, tau raug tsis saib xyuas thiab tsis tshua tham.Qhov kev tshuaj xyuas no tham txog cov txheej txheem hauv qab no txhawm rau txheeb xyuas peb hom qauv ntawm cov cuab yeej siv.
Cov qauv loj, cov qauv tsim, thiab tus naj npawb ntawm cov heterojunctions ntawm cov khoom siv ntsuas hauv hom I sensor tuaj yeem cuam tshuam rau qhov rhiab heev ntawm lub sensor.Tsis tas li ntawd, tus cwj pwm ntawm lub sensor kuj cuam tshuam los ntawm molar piv ntawm cov khoom.Hom II ntaus qauv txheej txheem (zoo nkauj heteronanostructures, bilayer lossis ntau cov cuab yeej nrov, hssns) yog cov khoom siv nrov tshaj plaws, thiab tsuas yog ib qho sib txuas nrog electrode.Rau cov qauv ntaus ntawv no, txiav txim siab qhov chaw conduction channel thiab lawv cov txheeb ze hloov yog qhov tseem ceeb hauv kev kawm cov txheej txheem ntawm kev xaav.Vim tias hom II cov cuab yeej suav nrog ntau qhov sib txawv ntawm cov kab ke heteronanostructures, ntau yam sib txawv ntawm kev hnov mob tau raug npaj.Hauv ib hom III cov kev sib txawv, cov channel conduction yog yeej los ntawm herojunction tsim nyob rau ntawm Heterifittion, thiab kev nkag siab me ntsis kev sib txawv yog qhov sib txawv.Yog li ntawd, nws yog ib qho tseem ceeb kom txiav txim siab qhov hloov hauv qhov siab ntawm heterojunittion barrier tom qab raug cov roj kom raug rau cov hom III sensor.Nrog rau qhov tsim no, tus kheej-powered photovoltaic gas sensors tuaj yeem ua kom txo tau lub zog noj.Txawm li cas los xij, txij li cov txheej txheem fabrication tam sim no yog qhov yooj yim thiab rhiab tau ntau dua li cov pa ntawm Mos-sensors, tseem muaj ntau yam kev nce qib hauv kev tshawb fawb ntawm tus kheej lub peev txheej ntawm tus kheej.
Lub ntsiab zoo ntawm cov pa roj MOS sensors nrog hierarchical heteronanostructures yog qhov ceev thiab siab dua.Txawm li cas los xij, qee qhov teeb meem tseem ceeb ntawm MOS roj sensors (xws li, kev ua haujlwm kub, kev ruaj ntseg mus ntev, kev xaiv tsis zoo thiab kev tsim tawm, cov av noo, thiab lwm yam) tseem muaj nyob thiab yuav tsum tau hais ua ntej lawv tuaj yeem siv rau hauv cov ntawv thov.Niaj hnub nimno MOS roj sensors feem ntau ua haujlwm ntawm qhov kub thiab txias thiab siv ntau lub zog, uas cuam tshuam rau lub sijhawm ntev ntawm lub sensor.Muaj ob txoj hauv kev los daws qhov teeb meem no: (1) kev txhim kho ntawm cov hluav taws xob tsis tshua muaj zog sensor chips;(2) kev tsim cov ntaub ntawv rhiab heev uas tuaj yeem ua haujlwm ntawm qhov kub thiab txias lossis txawm nyob hauv chav tsev kub.Ib txoj hauv kev rau kev txhim kho cov khoom siv hluav taws xob tsawg tsawg yog kom txo qhov loj ntawm lub sensor los ntawm kev tsim cov phaj microheating raws li ceramics thiab silicon163.Ceramic raws li micro cua sov phaj noj kwv yees li 50-70 mV ib lub sensor, thaum optimized silicon raws li micro cua sov daim hlau yuav haus tsawg li 2 mW ib sensor thaum ua hauj lwm tsis tu ncua ntawm 300 ° C163,164.Txoj kev loj hlob ntawm cov ntaub ntawv rhiab heev yog ib txoj hauv kev zoo los txo qis kev siv hluav taws xob los ntawm kev txo qis kev khiav hauj lwm kub, thiab tuaj yeem txhim kho kev ruaj ntseg sensor.Raws li qhov loj ntawm MOS txuas ntxiv raug txo kom nce qhov rhiab heev ntawm lub sensor, lub thermal stability ntawm MOS ua ntau dua ntawm kev sib tw, uas tuaj yeem ua rau drift hauv lub sensor signal165.Tsis tas li ntawd, qhov kub thiab txias txhawb nqa qhov sib txawv ntawm cov ntaub ntawv ntawm heterointerface thiab tsim cov theem sib xyaw, uas cuam tshuam rau cov khoom siv hluav taws xob ntawm lub sensor.Cov kws tshawb fawb tau tshaj tawm tias qhov kev ua haujlwm zoo tshaj plaws ntawm lub ntsuas hluav taws xob tuaj yeem raug txo los ntawm kev xaiv cov ntaub ntawv tsim nyog thiab tsim MOS heteronanostructures.Kev tshawb nrhiav rau txoj kev ntsuas kub qis rau kev tsim cov crystalline MOS heteronanostructures yog lwm txoj hauv kev los txhim kho kev ruaj ntseg.
Kev xaiv ntawm MOS sensors yog lwm qhov teeb meem zoo li cov roj sib txawv sib koom ua ke nrog lub hom phiaj roj, thaum MOS sensors feem ntau nkag siab rau ntau dua ib qho roj thiab feem ntau pom qhov sib txawv.Yog li ntawd, nce kev xaiv ntawm lub sensor mus rau lub hom phiaj roj nrog rau lwm cov pa roj yog qhov tseem ceeb rau kev siv tswv yim.Ob peb lub xyoo dhau los, kev xaiv tau ib feem los ntawm lub tsev arrays ntawm cov roj sensors hu ua "electronic noses (E-nose)" ua ke nrog kev txheeb xyuas kev txheeb xyuas algorithms xws li kev cob qhia vector quantization (LVQ), kev tsom xam cov ntsiab lus tseem ceeb (PCA), lwm e.Teeb meem kev sib deev.Ib feem tsawg Squares (PLS), thiab lwm yam. 31, 32, 33, 34. Ob yam tseem ceeb (cov naj npawb ntawm cov sensors, uas yog ze ze rau cov khoom siv sensing, thiab kev txheeb xyuas kev suav) yog qhov tseem ceeb rau kev txhim kho lub peev xwm ntawm hluav taws xob qhov ntswg. los txheeb xyuas gases169.Txawm li cas los xij, nce tus naj npawb ntawm cov sensors feem ntau yuav tsum muaj ntau txoj kev tsim khoom, yog li nws yog ib qho tseem ceeb kom nrhiav tau txoj hauv kev yooj yim los txhim kho kev ua haujlwm ntawm lub qhov ntswg hluav taws xob.Tsis tas li ntawd, kev hloov kho MOS nrog rau lwm cov ntaub ntawv kuj tuaj yeem ua rau muaj kev xaiv ntawm lub sensor.Piv txwv li, kev xaiv nrhiav H2 tuaj yeem ua tiav vim qhov kev ua haujlwm catalytic zoo ntawm MOS hloov nrog NP Pd.Nyob rau hauv xyoo tas los no, qee cov kws tshawb fawb tau coated MOS MOF nto los txhim kho qhov kev xaiv sensor los ntawm qhov loj me me 171,172.Kev tshoov siab los ntawm txoj haujlwm no, cov khoom siv ua haujlwm tuaj yeem daws qhov teeb meem ntawm kev xaiv.Txawm li cas los xij, tseem muaj ntau txoj haujlwm yuav tsum tau ua nyob rau hauv kev xaiv cov khoom tsim nyog.
Lub repeatability ntawm cov yam ntxwv ntawm sensors tsim nyob rau hauv tib yam kev mob thiab txoj kev yog ib qho tseem ceeb yuav tsum tau rau loj-scale ntau lawm thiab siv tswv yim.Feem ntau, centrifugation thiab dipping txoj kev yog cov nqi qis rau kev tsim cov pa hluav taws xob siab.Txawm li cas los xij, thaum lub sij hawm cov txheej txheem no, cov khoom rhiab heev yuav sib sau ua ke thiab kev sib raug zoo ntawm cov khoom rhiab thiab cov substrate ua tsis muaj zog 68, 138, 168. Yog li ntawd, qhov rhiab heev thiab kev ruaj ntseg ntawm lub sensor deteriorate heev, thiab kev ua tau zoo yuav rov ua dua.Lwm txoj kev tsim khoom xws li sputtering, ALD, pulsed laser deposition (PLD), thiab lub cev vapor deposition (PVD) tso cai rau zus tau tej cov bilayer los yog multilayer MOS films ncaj qha rau ntawm patterned silicon los yog alumina substrates.Cov txheej txheem no zam kev tsim cov ntaub ntawv rhiab heev, ua kom lub cev muaj zog dua, thiab ua kom pom qhov ua tau zoo ntawm cov khoom loj ntawm cov phiaj xwm nyias nyias.Txawm li cas los xij, qhov rhiab heev ntawm cov yeeb yaj kiab ca no feem ntau qis dua li ntawm 3D nanostructured cov ntaub ntawv vim lawv qhov chaw me me thiab cov pa roj tsawg permeability41,174.Cov tswv yim tshiab rau kev loj hlob MOS heteronanostructures ntawm cov chaw tshwj xeeb ntawm cov qauv microarrays thiab kev tswj xyuas qhov loj, tuab, thiab cov qauv ntawm cov ntaub ntawv rhiab heev yog qhov tseem ceeb rau kev tsim cov khoom siv qis ntawm wafer-theem sensors nrog siab rov tsim dua thiab rhiab heev.Piv txwv li, Liu et al.174 tau npaj ib qho kev sib koom ua ke saum toj-down thiab hauv qab-up lub tswv yim rau fabricating high-throughput crystallites los ntawm kev loj hlob hauv situ Ni (OH) 2 nanowalls ntawm qhov chaw tshwj xeeb..Wafers rau microburners.
Tsis tas li ntawd, nws tseem ceeb heev uas yuav tau xav txog qhov cuam tshuam ntawm cov av noo ntawm lub sensor hauv kev siv tswv yim.Dej lwg me me tuaj yeem sib tw nrog cov pa roj oxygen rau cov khoom seem adsorption hauv sensor cov ntaub ntawv thiab cuam tshuam rau lub luag haujlwm ntawm lub hom phiaj roj.Xws li cov pa oxygen, dej ua raws li cov molecule los ntawm kev ua si lub cev, thiab tseem muaj nyob rau hauv cov qauv ntawm cov pab pawg hydroxyl ntawm ntau cov chaw nres tsheb oxidation los ntawm kev ua tshuaj chemisoration.Tsis tas li ntawd, vim muaj qib siab thiab cov av sib txawv ntawm ib puag ncig, ib qho kev teb zoo ntawm lub sensor rau lub hom phiaj roj yog qhov teeb meem loj.Ob peb lub tswv yim tau tsim los daws cov teeb meem no, xws li roj ua ntej lub ntsej muag thiab cov huab cua kev ua kom noo noo thiab cov ntoo khaub ncaws ua kom muaj kev tshem tawm ntawm cov hau kev cav179,180.Txawm li cas los xij, cov txheej txheem no yog kim, nyuaj, thiab txo qhov rhiab heev ntawm lub sensor.Ob peb lub tswv yim pheej yig tau raug npaj los txhawm rau txo qis cov av noo.Piv txwv li, kho kom zoo nkauj SnO2 nrog Pd nanoparticles tuaj yeem txhawb kev hloov pauv ntawm cov pa oxygen adsorbed rau hauv anionic hais, thaum ua haujlwm SnO2 nrog cov ntaub ntawv muaj kev sib raug zoo rau cov dej molecules, xws li NiO thiab CuO, yog ob txoj hauv kev los tiv thaiv cov dej noo ntawm cov dej molecules..Sensors 181, 182, 183. Tsis tas li ntawd, cov nyhuv ntawm cov av noo kuj tuaj yeem txo tau los ntawm kev siv cov khoom siv hydrophobic los ua hydrophobic nto36,138,184,185.Txawm li cas los xij, txoj kev loj hlob ntawm cov roj av tiv thaiv kev tiv thaiv tseem nyob rau theem pib, thiab cov tswv yim zoo tshaj yuav tsum tau los daws cov teeb meem no.
Hauv kev xaus, kev txhim kho hauv kev ua tau zoo (piv txwv, kev xaiv ua haujlwm, qis dua kev ua haujlwm tau zoo) tau tiav los ntawm kev tsim kev txhim kho ntawm kev txhim kho ntawm kev txhim kho ntawm kev txhim kho ntawm kev txhim kho Mos paug, thiab ntau yam kev txhim kho kev txhim kho kom zoo dua qub.Thaum kawm txog kev hnov mob ntawm ib qho sensor, cov qauv geometric ntawm lub cuab yeej yuav tsum raug coj mus rau hauv tus account.Tshawb nrhiav rau cov ntaub ntawv zoo tshiab thiab tshawb fawb mus rau cov tswv yim pab ntoo siab yuav tsum tau txhim kho kev ua tau zoo ntawm cov kev sib tw ntawm yav tom ntej.Rau kev tswj hwm kev tswj hwm ntawm cov yam ntxwv sensor, nws yog qhov tsim nyog rau kev ua kom sib raug zoo ntawm cov khoom siv hluavtaws ntawm cov ntaub ntawv ntawm heteronanostructures.Ib qho ntxiv, kev kawm txog cov kev tawm tsam nto thiab hloov pauv hauv txoj kev ua kom muaj zog niaj hnub thiab muab cov lus pom zoo rau kev txhim kho ntawm cov ntaub ntawv ntawm Heriananostration.Thaum kawg, txoj kev kawm ntawm cov tswv yim zoo niaj hnub no tuaj yeem cia cov khoom siv ntawm cov roj ntsha sensors ntawm kev nyab xeeb rau lawv cov ntawv thov kev lag luam.
Genzel, NN et al.Txoj kev tshawb nrhiav ntev ntawm cov qib nitrogen dioxide hauv tsev thiab cov tsos mob ua pa ntawm cov menyuam yaus uas muaj mob hawb pob hauv nroog.zej zog.Kev xav txog kev noj qab haus huv.116, 1428–1432 (2008).
Post lub sij hawm: Nov-04-2022
