Wide bandgap (WBG) semiconductors sawv cev los ntawm silicon carbide (SiC) thiab gallium nitride (GaN) tau txais kev saib xyuas dav. Cov neeg muaj kev cia siab siab rau daim ntawv thov kev cia siab ntawm silicon carbide nyob rau hauv lub tsheb fais thiab fais fab, nrog rau daim ntawv thov prospects ntawm gallium nitride nyob rau hauv ceev them. Nyob rau hauv xyoo tas los no, kev tshawb fawb ntawm Ga2O3, AlN thiab cov ntaub ntawv pob zeb diamond tau ua kom muaj kev vam meej, ua rau cov ntaub ntawv ultra-wide bandgap semiconductor ua kom pom tseeb. Ntawm lawv, gallium oxide (Ga2O3) yog cov khoom siv ultra-wide-wide-bandgap semiconductor uas muaj qhov sib txawv ntawm 4.8 eV, qhov theoretical tseem ceeb ntawm lub zog tawg ntawm kwv yees li 8 MV cm-1, saturation tshaj tawm txog 2E7cm s-1, thiab qhov zoo tshaj plaws ntawm Baliga ntawm 3000, tau txais kev saib xyuas thoob plaws hauv thaj chaw muaj hluav taws xob thiab siab. zaus fais fab electronics.
1. Gallium oxide khoom yam ntxwv
Ga2O3 muaj qhov sib txawv loj (4.8 eV), yuav tsum ua tiav ob qho tib si siab tiv taus hluav taws xob thiab lub zog hluav taws xob muaj peev xwm, thiab tuaj yeem muaj lub peev xwm rau kev hloov pauv hluav taws xob siab ntawm qhov tsis kam tiv thaiv, ua rau lawv lub hom phiaj ntawm kev tshawb fawb tam sim no. Tsis tas li ntawd, Ga2O3 tsis tsuas yog muaj cov khoom siv zoo heev, tab sis kuj muab ntau yam kev hloov kho tau yooj yim n-hom doping technologies, nrog rau cov nqi qis qis qis thiab cov thev naus laus zis epitaxy. Txog tam sim no, tsib theem sib txawv siv lead ua tau pom nyob rau hauv Ga2O3, suav nrog corundum (α), monoclinic (β), tsis zoo spinel (γ), cubic (δ) thiab orthorhombic (ɛ) theem. Thermodynamic stability yog, nyob rau hauv kev txiav txim, γ, δ, α, ɛ, thiab β. Nws yog tsim nyog sau cia tias monoclinic β-Ga2O3 yog qhov ruaj khov tshaj plaws, tshwj xeeb tshaj yog nyob rau hauv qhov kub thiab txias, thaum lwm theem yog metastable saum chav tsev kub thiab zoo li hloov mus rau β theem nyob rau hauv tej yam kev mob thermal. Yog li ntawd, kev txhim kho ntawm β-Ga2O3-raws li cov khoom siv tau dhau los ua qhov tseem ceeb hauv kev lag luam hluav taws xob hluav taws xob hauv xyoo tas los no.
Table 1 Kev sib piv ntawm qee cov khoom siv hluav taws xob semiconductor
Cov qauv siv lead ua ntawm monoclinicβ-Ga2O3 yog qhia hauv Table 1. Nws cov lattice tsis muaj xws li a = 12.21 Å, b = 3.04 Å, c = 5.8 Å, thiab β = 103.8 °. Chav tsev cell muaj Ga(I) atoms nrog twisted tetrahedral coordination thiab Ga(II) atoms nrog octahedral coordination. Muaj peb qhov sib txawv ntawm cov pa oxygen atoms nyob rau hauv "twisted cubic" array, nrog rau ob lub triangularly koom tes O (I) thiab O (II) atoms thiab ib tug tetrahedrally coordinated O (III) atom. Kev sib xyaw ua ke ntawm ob hom kev sib koom ua ke atomic no ua rau anisotropy ntawm β-Ga2O3 nrog cov khoom tshwj xeeb hauv physics, tshuaj corrosion, optics thiab electronics.
Daim duab 1 Schematic structural daim duab ntawm monoclinic β-Ga2O3 siv lead ua
Los ntawm qhov kev xav ntawm lub zog band txoj kev xav, qhov tsawg kawg nkaus tus nqi ntawm cov conduction band ntawm β-Ga2O3 yog muab los ntawm lub zog lub xeev sib haum mus rau 4s0 hybrid orbit ntawm Ga atom. Lub zog sib txawv ntawm qhov tsawg kawg nkaus tus nqi ntawm cov conduction band thiab lub tshuab nqus tsev zog (electron affinity zog) yog ntsuas. yog 4e v. Qhov zoo electron loj ntawm β-Ga2O3 yog ntsuas li 0.28-0.33 kuv thiab nws cov khoom siv hluav taws xob zoo. Txawm li cas los xij, qhov valence band siab tshaj plaws nthuav tawm qhov ntiav Ek nkhaus nrog qhov curvature tsawg heev thiab muaj zog hauv zos O2p orbitals, tawm tswv yim tias lub qhov yog nyob hauv zos. Cov yam ntxwv no ua rau muaj kev sib tw loj heev kom ua tiav p-hom doping hauv β-Ga2O3. Txawm hais tias P-hom doping tuaj yeem ua tiav, lub qhov μ tseem nyob rau theem qis heev. 2. Kev loj hlob ntawm bulk gallium oxide ib leeg siv lead ua Kom deb li deb, txoj kev loj hlob ntawm β-Ga2O3 bulk ib leeg siv lead ua substrate feem ntau siv lead ua rub txoj kev, xws li Czochralski (CZ), ntug-txhais nyias zaj duab xis pub txoj kev (Edge-Defined film-fed , EFG), Bridgman (rtical los yog kab rov tav Bridgman, HB los yog VB) thiab floating zone (floating zone, FZ) technology. Ntawm txhua txoj hauv kev, Czochralski thiab ntug-txhais nyias-zaj duab xis pub txoj kev yuav tsum yog txoj hauv kev zoo tshaj plaws rau kev tsim khoom loj ntawm β-Ga 2O3 wafers yav tom ntej, vim lawv tuaj yeem ua tiav ib txhij ua tiav qhov ntim loj thiab qhov tsis xws luag. Txog rau tam sim no, Nyiv Novel Crystal Technology tau paub txog kev lag luam matrix rau kev loj hlob β-Ga2O3.
1.1 Czochralski txoj kev
Lub hauv paus ntsiab lus ntawm Czochralski txoj kev yog tias cov noob txheej yog thawj zaug, thiab tom qab ntawd ib qho siv lead ua maj mam rub tawm ntawm yaj. Txoj kev Czochralski yog qhov tseem ceeb rau β-Ga2O3 vim nws cov txiaj ntsig zoo, muaj peev xwm loj, thiab kev loj hlob zoo siv lead ua substrate. Txawm li cas los xij, vim yog thermal stress thaum lub sij hawm kub loj hlob ntawm Ga2O3, evaporation ntawm ib leeg muaju, yaj cov ntaub ntawv, thiab kev puas tsuaj rau Ir crucible yuav tshwm sim. Qhov no yog qhov tshwm sim ntawm qhov nyuaj hauv kev ua tiav qhov tsis tshua muaj n-hom doping hauv Ga2O3. Qhia kom tsim nyog cov pa oxygen rau hauv qhov chaw loj hlob yog ib txoj hauv kev los daws qhov teeb meem no. Los ntawm kev ua kom zoo, zoo 2-nti β-Ga2O3 nrog ib qho dawb electron concentration ntau ntawm 10^16 ~ 10^19 cm-3 thiab qhov siab tshaj plaws electron ceev ntawm 160 cm2 / Vs tau ntse zus los ntawm Czochralski txoj kev.
Daim duab 2 Ib leeg siv lead ua ntawm β-Ga2O3 zus los ntawm Czochralski txoj kev
1.2 Ntug-txhais zaj duab xis pub txoj kev
Lub ntug-txhais nyias zaj duab xis pub txoj kev yog suav tias yog tus thawj contender rau kev lag luam ntau lawm ntawm Ga2O3 ib leeg siv lead ua cov ntaub ntawv loj. Lub hauv paus ntsiab lus ntawm txoj kev no yog muab cov yaj nyob rau hauv lub pwm nrog ib tug capillary slit, thiab cov yaj nce mus rau pwm los ntawm capillary kev txiav txim. Nyob rau sab saum toj, ib daim duab nyias nyias thiab kis mus rau txhua qhov kev qhia thaum raug ntxias kom crystallize los ntawm cov noob siv lead ua. Tsis tas li ntawd, cov npoo ntawm cov pwm saum toj kawg nkaus tuaj yeem tswj tau los tsim cov khoom siv lead ua hauv flakes, raj, lossis txhua qhov xav tau geometry. Lub ntug-txhais nyias zaj duab xis pub txoj kev ntawm Ga2O3 muab kev loj hlob sai thiab loj diameters. Daim duab 3 qhia ib daim duab ntawm β-Ga2O3 ib leeg siv lead ua. Tsis tas li ntawd, nyob rau hauv cov nqe lus ntawm qhov loj me, 2-nti thiab 4-nti β-Ga2O3 substrates nrog zoo pob tshab thiab uniformity tau ua lag luam, thaum lub 6-nti substrate tau pom nyob rau hauv kev tshawb fawb rau yav tom ntej kev lag luam. Tsis ntev los no, cov ntaub ntawv loj loj ib leeg-crystal bulk kuj tau muaj nrog (−201) kev taw qhia. Tsis tas li ntawd, β-Ga2O3 ntug-txhais zaj duab xis pub txoj kev tseem txhawb nqa cov doping ntawm kev hloov pauv hlau, ua rau kev tshawb fawb thiab kev npaj ntawm Ga2O3 ua tau.
Daim duab 3 β-Ga2O3 ib leeg siv lead ua loj hlob los ntawm ntug-txhais zaj duab xis pub txoj kev
1.3 Txoj kev Bridgeman
Nyob rau hauv txoj kev Bridgeman, muaju yog tsim nyob rau hauv lub crucible uas maj mam txav los ntawm qhov kub thiab txias gradient. Cov txheej txheem tuaj yeem ua tau nyob rau hauv kab rov tav lossis ntsug, feem ntau yog siv lub rotating crucible. Nws tsim nyog sau cia tias txoj kev no tuaj yeem siv los yog tsis siv cov noob siv lead ua. Traditional Bridgman cov neeg ua haujlwm tsis muaj kev pom ncaj qha ntawm cov txheej txheem melting thiab siv lead ua kev loj hlob thiab yuav tsum tswj qhov kub thiab txias nrog qhov siab. Txoj kev ntsug Bridgman feem ntau yog siv rau kev loj hlob ntawm β-Ga2O3 thiab paub txog nws lub peev xwm loj hlob hauv huab cua ib puag ncig. Thaum lub sij hawm ntsug Bridgman txoj kev loj hlob txheej txheem, tag nrho cov huab hwm coj poob ntawm cov yaj thiab crucible yog khaws cia hauv qab 1%, ua kom txoj kev loj hlob ntawm loj β-Ga2O3 ib leeg muaju nrog tsawg tsawg.
Daim duab 4 Ib leeg siv lead ua ntawm β-Ga2O3 zus los ntawm Bridgeman txoj kev
1.4 Floating Zone txoj kev
Txoj kev floating cheeb tsam daws qhov teeb meem ntawm cov khoom siv lead ua paug los ntawm cov khoom siv crucible thiab txo cov nqi siab uas cuam tshuam nrog kub kub resistant infrared crucibles. Thaum lub sij hawm txoj kev loj hlob no, cov yaj tuaj yeem ua kom sov los ntawm lub teeb es tsis yog RF qhov chaw, yog li ua kom yooj yim rau cov khoom siv loj hlob. Txawm hais tias cov duab thiab siv lead ua zoo ntawm β-Ga2O3 loj hlob los ntawm txoj kev ntab hauv av tseem tsis tau pom zoo, txoj kev no qhib txoj hauv kev cog lus rau kev loj hlob siab-purity β-Ga2O3 rau hauv pob nyiaj siv rau ib leeg siv lead ua.
Daim duab 5 β-Ga2O3 ib leeg siv lead ua loj hlob los ntawm txoj kev floating zone.
Post lub sij hawm: May-30-2024