1. Cov khoom siv semiconductor tiam thib peb
Cov thev naus laus zis semiconductor thawj tiam tau tsim los ntawm cov khoom siv semiconductor xws li Si thiab Ge. Nws yog lub hauv paus rau kev txhim kho cov transistors thiab cov thev naus laus zis integrated circuit. Cov ntaub ntawv semiconductor thawj tiam tau tsim lub hauv paus rau kev lag luam hluav taws xob hauv xyoo pua 20th thiab yog cov ntaub ntawv tseem ceeb rau cov thev naus laus zis integrated circuit.
Cov ntaub ntawv semiconductor tiam thib ob feem ntau suav nrog gallium arsenide, indium phosphide, gallium phosphide, indium arsenide, txhuas arsenide thiab lawv cov khoom sib xyaw ua ke. Cov ntaub ntawv semiconductor tiam thib ob yog lub hauv paus ntawm kev lag luam optoelectronic. Ntawm lub hauv paus no, kev lag luam cuam tshuam xws li teeb pom kev zoo, zaub, laser, thiab photovoltaics tau tsim. Lawv tau siv dav hauv kev siv tshuab niaj hnub no thiab kev lag luam optoelectronic zaub.
Cov ntaub ntawv sawv cev ntawm cov ntaub ntawv semiconductor tiam thib peb suav nrog gallium nitride thiab silicon carbide. Vim lawv qhov sib txawv ntawm cov kab dav, qhov ceev ntawm electron saturation drift, thermal conductivity siab, thiab lub zog tawg siab, lawv yog cov ntaub ntawv zoo tagnrho rau kev npaj cov khoom siv hluav taws xob siab, zaus siab, thiab poob qis. Ntawm lawv, cov khoom siv hluav taws xob silicon carbide muaj qhov zoo ntawm lub zog siab, kev siv hluav taws xob tsawg, thiab qhov me me, thiab muaj kev cia siab dav hauv cov tsheb fais fab tshiab, photovoltaics, kev thauj mus los ntawm tsheb ciav hlau, cov ntaub ntawv loj, thiab lwm yam. Gallium nitride RF cov khoom siv muaj qhov zoo ntawm zaus siab, lub zog siab, bandwidth dav, kev siv hluav taws xob tsawg thiab qhov me me, thiab muaj kev cia siab dav hauv kev sib txuas lus 5G, Internet of Things, tub rog radar thiab lwm yam. Tsis tas li ntawd, cov khoom siv hluav taws xob gallium nitride tau siv dav hauv thaj chaw qis-voltage. Tsis tas li ntawd, nyob rau xyoo tas los no, cov ntaub ntawv gallium oxide tshiab xav tias yuav tsim kev sib txuas lus nrog cov thev naus laus zis SiC thiab GaN uas twb muaj lawm, thiab muaj peev xwm thov tau hauv thaj chaw qis-zaus thiab siab-voltage.
Piv nrog rau cov ntaub ntawv semiconductor tiam thib ob, cov ntaub ntawv semiconductor tiam thib peb muaj qhov dav bandgap dav dua (qhov dav bandgap ntawm Si, ib yam khoom siv ntawm cov ntaub ntawv semiconductor tiam thawj zaug, yog li 1.1 eV, qhov dav bandgap ntawm GaAs, ib yam khoom siv ntawm cov ntaub ntawv semiconductor tiam thib ob, yog li 1.42 eV, thiab qhov dav bandgap ntawm GaN, ib yam khoom siv ntawm cov ntaub ntawv semiconductor tiam thib peb, yog siab dua 2.3 eV), muaj zog tiv taus hluav taws xob, muaj zog tiv taus hluav taws xob tawg, thiab kub dua. Cov ntaub ntawv semiconductor tiam thib peb nrog qhov dav bandgap dav dua yog qhov tsim nyog rau kev tsim cov khoom siv hluav taws xob tiv taus hluav taws xob, zaus siab, muaj zog siab thiab muaj kev sib koom ua ke siab. Lawv daim ntawv thov hauv cov khoom siv microwave xov tooj cua zaus, LEDs, lasers, cov khoom siv fais fab thiab lwm yam teb tau nyiam ntau qhov kev saib xyuas, thiab lawv tau pom cov kev cia siab dav hauv kev sib txuas lus txawb, cov phiaj xwm ntse, kev thauj mus los ntawm tsheb ciav hlau, tsheb fais fab tshiab, cov khoom siv hluav taws xob rau cov neeg siv khoom, thiab cov khoom siv ultraviolet thiab xiav-ntsuab [1].
Duab los ntawm: CASA, Zheshang Securities Research Institute
Daim Duab 1 Lub sijhawm ntsuas thiab kev kwv yees ntawm GaN lub zog fais fab
II GaN cov qauv khoom siv thiab cov yam ntxwv
GaN yog ib lub semiconductor bandgap ncaj qha. Qhov dav ntawm bandgap ntawm cov qauv wurtzite ntawm chav tsev kub yog li 3.26 eV. Cov ntaub ntawv GaN muaj peb lub qauv siv lead ua tseem ceeb, uas yog cov qauv wurtzite, cov qauv sphalerite thiab cov qauv ntsev pob zeb. Ntawm lawv, cov qauv wurtzite yog cov qauv siv lead ua ruaj khov tshaj plaws. Daim duab 2 yog daim duab ntawm cov qauv wurtzite hexagonal ntawm GaN. Cov qauv wurtzite ntawm cov ntaub ntawv GaN koom nrog cov qauv kaw hexagonal. Txhua lub cell muaj 12 atoms, suav nrog 6 N atoms thiab 6 Ga atoms. Txhua Ga (N) atom tsim ib qho kev sib txuas nrog 4 N (Ga) atoms ze tshaj plaws thiab tau teeb tsa raws li qhov kev txiav txim ntawm ABABAB… raws li [0001] kev taw qhia [2].
Daim Duab 2 Wurtzite qauv GaN crystal cell daim duab
III Feem ntau siv cov substrates rau GaN epitaxy
Zoo li homogeneous epitaxy ntawm GaN substrates yog qhov kev xaiv zoo tshaj plaws rau GaN epitaxy. Txawm li cas los xij, vim yog lub zog loj ntawm GaN, thaum qhov kub thiab txias mus txog qhov melting point ntawm 2500 ℃, nws qhov kev sib cais sib xws yog li 4.5GPa. Thaum qhov kev sib cais siab qis dua qhov siab no, GaN tsis yaj tab sis decomposes ncaj qha. Qhov no ua rau cov txheej txheem npaj substrate mature xws li Czochralski txoj kev tsis haum rau kev npaj ntawm GaN ib leeg siv lead ua substrates, ua rau GaN substrates nyuaj rau tsim ntau thiab kim. Yog li ntawd, cov substrates feem ntau siv hauv GaN epitaxial kev loj hlob yog feem ntau Si, SiC, sapphire, thiab lwm yam. [3].
Daim Ntawv Qhia 3 GaN thiab cov kev ntsuas ntawm cov ntaub ntawv siv feem ntau
GaN epitaxy ntawm sapphire
Sapphire muaj cov khoom siv tshuaj ruaj khov, pheej yig, thiab muaj kev loj hlob siab ntawm kev lag luam loj. Yog li ntawd, nws tau dhau los ua ib qho ntawm cov ntaub ntawv substrate thaum ntxov thiab siv dav tshaj plaws hauv kev tsim khoom siv semiconductor. Raws li ib qho ntawm cov substrates siv rau GaN epitaxy, cov teeb meem tseem ceeb uas yuav tsum tau daws rau sapphire substrates yog:
✔ Vim yog qhov sib txawv ntawm sapphire (Al2O3) thiab GaN (kwv yees li 15%), qhov ceev ntawm qhov sib txuas ntawm cov txheej epitaxial thiab cov substrate siab heev. Yuav kom txo tau nws cov teebmeem tsis zoo, cov substrate yuav tsum tau ua ntej ua ntej pib txheej txheem epitaxy. Ua ntej cog GaN epitaxy ntawm sapphire substrates, qhov chaw substrate yuav tsum tau ntxuav kom huv si kom tshem tawm cov kuab paug, cov khoom seem polishing puas tsuaj, thiab lwm yam, thiab los tsim cov kauj ruam thiab cov qauv nto. Tom qab ntawd, qhov chaw substrate yog nitrided los hloov cov khoom ntub ntawm cov txheej epitaxial. Thaum kawg, ib txheej AlN buffer nyias (feem ntau yog 10-100nm tuab) yuav tsum tau tso rau ntawm qhov chaw substrate thiab annealed ntawm qhov kub qis los npaj rau qhov kawg epitaxial loj hlob. Txawm li ntawd los, qhov ceev ntawm qhov dislocation hauv GaN epitaxial zaj duab xis uas cog rau ntawm sapphire substrates tseem siab dua li ntawm cov zaj duab xis homoepitaxial (kwv yees li 1010cm-2, piv nrog qhov ceev ntawm qhov dislocation xoom hauv silicon homoepitaxial zaj duab xis lossis gallium arsenide homoepitaxial zaj duab xis, lossis ntawm 102 thiab 104cm-2). Qhov ceev ntawm qhov tsis zoo siab dua txo qhov kev txav mus los ntawm cov neeg nqa khoom, yog li ua rau lub neej ntawm cov neeg nqa khoom tsawg dua thiab txo cov thermal conductivity, tag nrho cov no yuav txo qhov kev ua haujlwm ntawm lub cuab yeej [4];
✔ Tus coefficient ntawm thermal expansion ntawm sapphire yog ntau dua li ntawm GaN, yog li biaxial compressive stress yuav raug tsim nyob rau hauv epitaxial txheej thaum lub sijhawm txias los ntawm qhov kub thiab txias mus rau chav tsev kub. Rau cov yeeb yaj kiab epitaxial tuab dua, qhov kev ntxhov siab no yuav ua rau zaj duab xis lossis txawm tias lub substrate tawg;
✔ Piv nrog rau lwm cov substrates, qhov thermal conductivity ntawm sapphire substrates qis dua (kwv yees li 0.25W * cm-1 * K-1 ntawm 100 ℃), thiab qhov kev ua haujlwm dissipation cua sov tsis zoo;
✔ Vim nws txoj kev coj ua hluav taws xob tsis zoo, cov khoom siv sapphire tsis zoo rau lawv txoj kev koom ua ke thiab daim ntawv thov nrog lwm cov khoom siv semiconductor.
Txawm hais tias qhov tsis zoo ntawm GaN epitaxial txheej loj hlob ntawm sapphire substrates siab, nws zoo li tsis txo qhov kev ua tau zoo ntawm optoelectronic ntawm GaN-based xiav-ntsuab LEDs, yog li sapphire substrates tseem yog cov substrates siv rau GaN-based LEDs.
Nrog rau kev tsim cov ntawv thov tshiab ntawm GaN cov khoom siv xws li lasers lossis lwm yam khoom siv fais fab siab, qhov tsis zoo ntawm sapphire substrates tau dhau los ua qhov txwv rau lawv daim ntawv thov. Tsis tas li ntawd, nrog rau kev tsim cov thev naus laus zis loj hlob ntawm SiC substrate, kev txo nqi thiab kev loj hlob ntawm GaN epitaxial technology ntawm Si substrates, kev tshawb fawb ntxiv txog kev loj hlob ntawm GaN epitaxial txheej ntawm sapphire substrates tau maj mam qhia txog qhov sib txawv txias.
GaN epitaxy ntawm SiC
Piv nrog sapphire, SiC substrates (4H- thiab 6H-crystals) muaj qhov sib txawv me me nrog GaN epitaxial txheej (3.1%, sib npaug rau [0001] oriented epitaxial zaj duab xis), thermal conductivity siab dua (kwv yees li 3.8W * cm-1 * K-1), thiab lwm yam. Tsis tas li ntawd, qhov conductivity ntawm SiC substrates kuj tso cai rau kev sib cuag hluav taws xob ua rau sab nraub qaum ntawm lub substrate, uas pab ua kom yooj yim rau cov qauv cuab yeej. Qhov muaj cov txiaj ntsig no tau nyiam ntau thiab ntau tus kws tshawb fawb los ua haujlwm ntawm GaN epitaxy ntawm silicon carbide substrates.
Txawm li cas los xij, ua haujlwm ncaj qha rau ntawm SiC substrates kom tsis txhob loj hlob GaN epilayers kuj ntsib ntau yam tsis zoo, suav nrog cov hauv qab no:
✔ Qhov roughness ntawm SiC substrates yog siab dua li ntawm sapphire substrates (sapphire roughness 0.1nm RMS, SiC roughness 1nm RMS), SiC substrates muaj qhov nyuaj siab thiab kev ua haujlwm tsis zoo, thiab qhov roughness thiab kev puas tsuaj polishing seem no kuj yog ib qho ntawm cov qhov tsis zoo hauv GaN epilayers.
✔ Qhov ceev ntawm cov ntsia hlau dislocation ntawm SiC substrates yog siab (dislocation density 103-104cm-2), cov ntsia hlau dislocations yuav kis mus rau GaN epilayer thiab txo cov khoom siv ua haujlwm;
✔ Qhov kev npaj atomic ntawm qhov chaw substrate ua rau muaj kev tsim cov stacking faults (BSFs) hauv GaN epilayer. Rau epitaxial GaN ntawm SiC substrates, muaj ntau qhov ua tau atomic arrangement orders ntawm lub substrate, ua rau tsis sib xws thawj atomic stacking order ntawm epitaxial GaN txheej ntawm nws, uas yog fraught rau stacking faults. Stacking faults (SFs) qhia txog cov teb hluav taws xob ua ke raws c-axis, ua rau muaj teeb meem xws li xau ntawm cov khoom siv sib cais hauv dav hlau;
✔ Tus coefficient thermal expansion ntawm SiC substrate yog me dua li ntawm AlN thiab GaN, uas ua rau muaj kev ntxhov siab thermal ntawm cov txheej epitaxial thiab cov substrate thaum lub sijhawm txias. Waltereit thiab Brand tau kwv yees raws li lawv cov txiaj ntsig tshawb fawb tias qhov teeb meem no tuaj yeem daws tau lossis daws tau los ntawm kev loj hlob GaN epitaxial txheej ntawm cov txheej nyias nyias, sib xws AlN nucleation txheej;
✔ Qhov teeb meem ntawm qhov tsis zoo ntawm cov Ga atoms. Thaum cog cov txheej GaN epitaxial ncaj qha rau ntawm SiC nto, vim qhov tsis zoo ntawm ob lub atoms, GaN feem ntau yuav loj hlob 3D kob ntawm qhov chaw substrate. Kev qhia txog cov txheej buffer yog qhov kev daws teeb meem feem ntau siv los txhim kho qhov zoo ntawm cov ntaub ntawv epitaxial hauv GaN epitaxy. Kev qhia txog AlN lossis AlxGa1-xN buffer txheej tuaj yeem txhim kho qhov zoo ntawm SiC nto thiab ua rau GaN epitaxial txheej loj hlob hauv ob qhov ntev. Tsis tas li ntawd, nws kuj tseem tuaj yeem tswj kev ntxhov siab thiab tiv thaiv cov teeb meem substrate los ntawm kev nthuav dav mus rau GaN epitaxy;
✔ Cov txheej txheem npaj ntawm SiC substrates tseem tsis tau paub tab, tus nqi substrate siab, thiab muaj ob peb tus neeg muag khoom thiab me ntsis kev muab khoom.
Kev tshawb fawb ntawm Torres et al. qhia tau hais tias kev etching SiC substrate nrog H2 ntawm qhov kub siab (1600 ° C) ua ntej epitaxy tuaj yeem tsim cov qauv kauj ruam ntau dua ntawm qhov chaw substrate, yog li tau txais cov yeeb yaj kiab AlN epitaxial zoo dua li thaum nws loj hlob ncaj qha rau ntawm qhov chaw substrate qub. Kev tshawb fawb ntawm Xie thiab nws pab neeg kuj qhia tau hais tias kev etching pretreatment ntawm silicon carbide substrate tuaj yeem txhim kho qhov morphology ntawm qhov chaw thiab qhov zoo ntawm cov siv lead ua ntawm GaN epitaxial txheej. Smith et al. pom tias cov xov dislocations uas pib los ntawm cov txheej substrate/buffer thiab cov txheej buffer/epitaxial txheej interfaces muaj feem cuam tshuam nrog qhov tiaj tus ntawm cov substrate [5].
Daim Duab 4 TEM morphology ntawm GaN epitaxial txheej qauv loj hlob ntawm 6H-SiC substrate (0001) nyob rau hauv ntau yam kev kho mob nto (a) kev ntxuav tshuaj; (b) kev ntxuav tshuaj + kev kho hydrogen plasma; (c) kev ntxuav tshuaj + kev kho hydrogen plasma + 1300 ℃ hydrogen cua sov kho rau 30 feeb
GaN epitaxy ntawm Si
Piv nrog silicon carbide, sapphire thiab lwm yam substrates, cov txheej txheem npaj silicon substrate yog mature, thiab nws tuaj yeem muab cov substrates loj loj nrog kev ua tau zoo. Tib lub sijhawm, qhov thermal conductivity thiab hluav taws xob conductivity zoo, thiab cov txheej txheem Si hluav taws xob yog mature. Qhov ua tau ntawm kev sib koom ua ke zoo kawg nkaus optoelectronic GaN cov khoom siv nrog Si hluav taws xob cov khoom siv yav tom ntej kuj ua rau kev loj hlob ntawm GaN epitaxy ntawm silicon zoo nkauj heev.
Txawm li cas los xij, vim muaj qhov sib txawv loj ntawm cov lattice constants ntawm Si substrate thiab GaN cov khoom siv, heterogeneous epitaxy ntawm GaN ntawm Si substrate yog qhov sib txawv loj ntawm mismatch epitaxy, thiab nws kuj yuav tsum ntsib ntau yam teeb meem:
✔ Teeb meem zog ntawm qhov chaw sib txuas. Thaum GaN loj hlob ntawm Si substrate, qhov chaw ntawm Si substrate yuav raug nitrided ua ntej los tsim ib txheej amorphous silicon nitride uas tsis zoo rau kev tsim thiab kev loj hlob ntawm high-density GaN. Tsis tas li ntawd, qhov chaw Si yuav xub kov Ga, uas yuav ua rau qhov chaw ntawm Si substrate xeb. Thaum kub siab, qhov kev lwj ntawm Si nto yuav kis mus rau hauv GaN epitaxial txheej los tsim cov pob dub silicon.
✔ Qhov sib txawv ntawm GaN thiab Si yog loj heev (~ 17%), uas yuav ua rau muaj kev sib cais ntawm cov xov hlau thiab ua rau qhov zoo ntawm cov txheej epitaxial tsis zoo;
✔ Piv nrog Si, GaN muaj cov coefficient thermal expansion loj dua (GaN's thermal expansion coefficient yog li 5.6 × 10-6K-1, Si's thermal expansion coefficient yog li 2.6 × 10-6K-1), thiab cov kab nrib pleb yuav tshwm sim hauv GaN epitaxial txheej thaum lub sijhawm txias ntawm qhov kub epitaxial mus rau qhov kub hauv chav;
✔ Si cuam tshuam nrog NH3 ntawm qhov kub siab los tsim cov polycrystalline SiNx. AlN tsis tuaj yeem tsim ib lub nucleus uas nyiam nyob rau ntawm polycrystalline SiNx, uas ua rau muaj kev tsis sib haum xeeb ntawm cov txheej GaN uas loj hlob tom qab thiab muaj ntau qhov tsis zoo, ua rau cov khoom siv lead ua tsis zoo ntawm cov txheej GaN epitaxial, thiab txawm tias nyuaj rau tsim ib txheej GaN epitaxial ib leeg-crystalline [6].
Yuav kom daws tau qhov teeb meem ntawm qhov sib txawv ntawm cov lattice loj, cov kws tshawb fawb tau sim qhia cov ntaub ntawv xws li AlAs, GaAs, AlN, GaN, ZnO, thiab SiC ua cov txheej buffer ntawm Si substrates. Yuav kom tsis txhob muaj kev tsim cov polycrystalline SiNx thiab txo nws cov teebmeem tsis zoo rau qhov zoo ntawm cov khoom siv GaN / AlN / Si (111), TMAl feem ntau yuav tsum tau qhia rau ib lub sijhawm ua ntej kev loj hlob epitaxial ntawm AlN buffer txheej kom tiv thaiv NH3 los ntawm kev cuam tshuam nrog qhov chaw Si uas raug tsim los tsim SiNx. Tsis tas li ntawd, cov thev naus laus zis epitaxial xws li cov thev naus laus zis patterned substrate tuaj yeem siv los txhim kho qhov zoo ntawm cov txheej epitaxial. Kev txhim kho ntawm cov thev naus laus zis no pab tiv thaiv kev tsim ntawm SiNx ntawm qhov sib txuas epitaxial, txhawb kev loj hlob ob-seem ntawm GaN epitaxial txheej, thiab txhim kho qhov zoo ntawm kev loj hlob ntawm cov txheej epitaxial. Tsis tas li ntawd, ib txheej AlN buffer tau qhia los them rau qhov kev ntxhov siab tensile los ntawm qhov sib txawv ntawm cov coefficients thermal expansion kom tsis txhob muaj kab nrib pleb hauv GaN epitaxial txheej ntawm silicon substrate. Krost txoj kev tshawb fawb qhia tau hais tias muaj kev sib raug zoo ntawm qhov tuab ntawm AlN buffer txheej thiab qhov txo qis ntawm kev ntxhov siab. Thaum lub buffer txheej tuab ncav cuag 12nm, ib txheej epitaxial tuab dua 6μm tuaj yeem loj hlob ntawm silicon substrate los ntawm kev tsim txoj kev loj hlob tsim nyog yam tsis muaj epitaxial txheej tawg.
Tom qab kev siv zog ntev los ntawm cov kws tshawb fawb, qhov zoo ntawm GaN epitaxial txheej uas loj hlob ntawm silicon substrates tau zoo dua qub, thiab cov khoom siv xws li field effect transistors, Schottky barrier ultraviolet detectors, xiav-ntsuab LEDs thiab ultraviolet lasers tau ua tiav zoo heev.
Hauv kev xaus, txij li thaum cov khoom siv GaN epitaxial feem ntau yog heterogeneous epitaxy, lawv txhua tus ntsib teeb meem xws li lattice mismatch thiab qhov sib txawv loj hauv thermal expansion coefficients rau ntau qib. Homogeneous epitaxial GaN substrates raug txwv los ntawm kev loj hlob ntawm thev naus laus zis, thiab cov substrates tseem tsis tau tsim ntau. Tus nqi tsim khoom siab, qhov loj me ntawm substrate yog me me, thiab qhov zoo ntawm substrate tsis zoo tagnrho. Kev tsim cov khoom siv GaN epitaxial tshiab thiab kev txhim kho ntawm epitaxial zoo tseem yog ib qho tseem ceeb uas txwv tsis pub kev txhim kho ntxiv ntawm GaN epitaxial kev lag luam.
IV. Cov txheej txheem siv rau GaN epitaxy
MOCVD (tshuaj lom neeg tso pa tawm)
Zoo li homogeneous epitaxy ntawm GaN substrates yog qhov kev xaiv zoo tshaj plaws rau GaN epitaxy. Txawm li cas los xij, txij li thaum cov precursors ntawm cov tshuaj vapor deposition yog trimethylgallium thiab ammonia, thiab cov roj nqa yog hydrogen, qhov kub thiab txias ntawm MOCVD feem ntau yog li 1000-1100 ℃, thiab qhov nrawm ntawm MOCVD yog li ob peb microns ib teev. Nws tuaj yeem tsim cov interfaces ntxhab ntawm qib atomic, uas yog qhov tsim nyog rau kev loj hlob heterojunctions, quantum wells, superlattices thiab lwm yam qauv. Nws qhov nrawm nrawm, kev sib xws zoo, thiab kev haum rau thaj chaw loj thiab ntau daim kev loj hlob feem ntau siv rau hauv kev tsim khoom lag luam.
MBE (molecular beam epitaxy)
Hauv molecular beam epitaxy, Ga siv ib qho chaw elemental, thiab cov nitrogen nquag tau txais los ntawm nitrogen los ntawm RF plasma. Piv nrog rau txoj kev MOCVD, qhov kub ntawm MBE loj hlob yog li 350-400 ℃ qis dua. Qhov kub ntawm kev loj hlob qis dua tuaj yeem zam qee yam kev ua qias tuaj uas yuav tshwm sim los ntawm qhov chaw kub siab. Lub kaw lus MBE ua haujlwm nyob rau hauv lub tshuab nqus tsev ultra-siab, uas tso cai rau nws los koom ua ke ntau txoj hauv kev nrhiav pom hauv qhov chaw. Tib lub sijhawm, nws qhov kev loj hlob thiab lub peev xwm tsim khoom tsis tuaj yeem piv nrog MOCVD, thiab nws siv ntau dua hauv kev tshawb fawb [7].
Daim duab 5 (a) Eiko-MBE schematic (b) MBE lub ntsiab tshuaj tiv thaiv chamber schematic
Txoj kev HVPE (hydride vapor theem epitaxy)
Cov ua ntej ntawm txoj kev hydride vapor phase epitaxy yog GaCl3 thiab NH3. Detchprohm et al. siv txoj kev no los cog ib txheej GaN epitaxial pua pua microns tuab rau ntawm qhov chaw ntawm sapphire substrate. Hauv lawv qhov kev sim, ib txheej ntawm ZnO tau loj hlob ntawm sapphire substrate thiab txheej epitaxial ua ib txheej buffer, thiab txheej epitaxial tau tev tawm ntawm qhov chaw substrate. Piv nrog MOCVD thiab MBE, qhov tseem ceeb ntawm txoj kev HVPE yog nws qhov kev loj hlob siab, uas yog qhov tsim nyog rau kev tsim cov txheej tuab thiab cov ntaub ntawv loj. Txawm li cas los xij, thaum lub thickness ntawm txheej epitaxial tshaj 20μm, txheej epitaxial tsim los ntawm txoj kev no yuav tawg.
Akira USUI tau qhia txog cov thev naus laus zis patterned substrate raws li txoj kev no. Lawv thawj zaug loj hlob ib txheej nyias nyias 1-1.5μm tuab GaN epitaxial ntawm sapphire substrate siv txoj kev MOCVD. Cov txheej epitaxial muaj 20nm tuab GaN buffer txheej loj hlob nyob rau hauv qhov kub qis thiab ib txheej GaN loj hlob nyob rau hauv qhov kub siab. Tom qab ntawd, ntawm 430 ℃, ib txheej ntawm SiO2 tau plated rau ntawm qhov chaw ntawm epitaxial txheej, thiab cov kab txaij qhov rai tau ua rau ntawm zaj duab xis SiO2 los ntawm photolithography. Qhov sib nrug ntawm cov kab txaij yog 7μm thiab qhov dav ntawm lub ntsej muag ntau ntawm 1μm txog 4μm. Tom qab qhov kev txhim kho no, lawv tau txais ib txheej GaN epitaxial ntawm 2-nti txoj kab uas hla sapphire substrate uas tsis muaj qhov tawg thiab du zoo li daim iav txawm tias thaum qhov tuab nce mus txog kaum lossis txawm tias ntau pua microns. Qhov ntom ntawm qhov tsis xws luag tau txo qis los ntawm 109-1010cm-2 ntawm txoj kev HVPE ib txwm muaj txog li 6 × 107cm-2. Lawv kuj tau taw qhia hauv kev sim tias thaum tus nqi loj hlob tshaj 75μm / h, qhov chaw ntawm cov qauv yuav dhau los ua ntxhib [8].
Daim Duab 6 Daim Duab Qhia Txog Cov Khoom Siv
V. Kev Qhia Txog thiab Kev Cia Siab
Cov ntaub ntawv GaN tau pib tshwm sim hauv xyoo 2014 thaum lub teeb xiav LED yeej qhov khoom plig Nobel hauv Physics xyoo ntawd, thiab tau nkag mus rau hauv pej xeem qhov kev siv them ceev hauv cov khoom siv hluav taws xob rau cov neeg siv khoom. Qhov tseeb, cov ntawv thov hauv cov amplifiers fais fab thiab RF siv hauv 5G chaw nres tsheb uas feem ntau cov neeg tsis pom kuj tau tshwm sim ntsiag to. Nyob rau hauv xyoo tas los no, kev tawg ntawm GaN-raws li tsheb-qib fais fab khoom siv yuav qhib cov ntsiab lus tshiab rau kev lag luam daim ntawv thov khoom siv GaN.
Qhov kev thov loj heev ntawm kev ua lag luam yuav txhawb nqa kev txhim kho ntawm cov lag luam thiab cov thev naus laus zis ntsig txog GaN. Nrog rau kev loj hlob thiab kev txhim kho ntawm cov saw hlau kev lag luam ntsig txog GaN, cov teeb meem uas cov thev naus laus zis epitaxial GaN tam sim no ntsib yuav raug txhim kho lossis kov yeej. Yav tom ntej, tib neeg yuav tsim ntau cov thev naus laus zis epitaxial tshiab thiab ntau cov kev xaiv substrate zoo heev. Los ntawm lub sijhawm ntawd, tib neeg yuav muaj peev xwm xaiv cov thev naus laus zis tshawb fawb sab nraud thiab substrate tsim nyog tshaj plaws rau ntau qhov xwm txheej thov raws li cov yam ntxwv ntawm cov xwm txheej thov, thiab tsim cov khoom lag luam sib tw tshaj plaws.
Lub sijhawm tshaj tawm: Lub Rau Hli-28-2024