1. Ii-semiconductors zesizukulwana sesithathu
Itekhnoloji ye-semiconductor yesizukulwana sokuqala yaphuhliswa ngokusekelwe kwizixhobo ze-semiconductor ezifana ne-Si kunye ne-Ge. Yisiseko sezinto zophuhliso lwee-transistors kunye netekhnoloji yesekethe edibeneyo. Izixhobo ze-semiconductor zesizukulwana sokuqala zabeka isiseko soshishino lwe-elektroniki kwinkulungwane yama-20 kwaye zizixhobo ezisisiseko zobuchwepheshe besekethe edibeneyo.
Izixhobo ze-semiconductor zesizukulwana sesibini ziquka i-gallium arsenide, i-indium phosphide, i-gallium phosphide, i-indium arsenide, i-aluminium arsenide kunye neekhompawundi zazo ze-ternary. Izixhobo ze-semiconductor zesizukulwana sesibini zisisiseko soshishino lolwazi lwe-optoelectronic. Ngenxa yesi sizathu, amashishini anxulumeneyo afana nokukhanyisa, ukubonisa, i-laser, kunye ne-photovoltaics aye aphuhliswa. Zisetyenziswa kakhulu kumashishini olwazi lwanamhlanje kunye nokubonisa i-optoelectronic.
Izinto ezimele izixhobo ze-semiconductor zesizukulwana sesithathu ziquka i-gallium nitride kunye ne-silicon carbide. Ngenxa yesithuba sazo esikhulu sebhendi, isantya esiphezulu sokutyibilika kwe-electron saturation, ukuqhuba okuphezulu kobushushu, kunye namandla entsimi yokuqhekeka okuphezulu, zizixhobo ezifanelekileyo zokulungiselela izixhobo ze-elektroniki ezinobunzima obuphezulu, eziphindaphindayo, kunye nezilahleko eziphantsi. Phakathi kwazo, izixhobo zamandla ze-silicon carbide zineengenelo zobuninzi bamandla, ukusetyenziswa kwamandla aphantsi, kunye nobukhulu obuncinci, kwaye zineengenelo zokusetyenziswa ngokubanzi kwizithuthi zamandla amatsha, ii-photovoltaics, ukuthuthwa koololiwe, i-big data, kunye nezinye iindawo. Izixhobo ze-Gallium nitride RF zineengenelo zobuninzi obuphezulu, amandla aphezulu, i-bandwidth ebanzi, ukusetyenziswa kwamandla aphantsi kunye nobukhulu obuncinci, kwaye zineengenelo zokusetyenziswa ngokubanzi kunxibelelwano lwe-5G, kwi-Intanethi yezinto, kwi-radar yomkhosi nakwezinye iindawo. Ukongeza, izixhobo zamandla ezisekelwe kwi-gallium nitride zisetyenziswe kakhulu kwintsimi enombane ophantsi. Ukongeza, kwiminyaka yakutshanje, izinto ezisandula kuvela ze-gallium oxide kulindeleke ukuba zenze ukuhambelana kobuchwepheshe kunye nobuchwepheshe be-SiC kunye ne-GaN obukhoyo, kwaye zineengenelo zokusetyenziswa ezinokubakho kwiindawo ezinombane ophantsi kunye nombane ophakamileyo.
Xa kuthelekiswa nezixhobo ze-semiconductor zesizukulwana sesibini, izixhobo ze-semiconductor zesizukulwana sesithathu zinobubanzi be-bandgap ebanzi (ububanzi be-bandgap ye-Si, into eqhelekileyo yezinto ze-semiconductor zesizukulwana sokuqala, malunga ne-1.1eV, ububanzi be-bandgap ye-GaAs, into eqhelekileyo yezinto ze-semiconductor zesizukulwana sesibini, malunga ne-1.42eV, kwaye ububanzi be-bandgap ye-GaN, into eqhelekileyo yezinto ze-semiconductor zesizukulwana sesithathu, ingaphezulu kwe-2.3eV), ukumelana nemitha enamandla, ukumelana namandla okuqhekeka kwentsimi yombane, kunye nokumelana nobushushu obuphezulu. Izixhobo ze-semiconductor zesizukulwana sesithathu ezinobubanzi be-bandgap ebanzi zifanelekile ngokukodwa kwimveliso yezixhobo ze-elektroniki ezimelana nemitha, ezisebenzisa i-frequency ephezulu, ezinamandla aphezulu kunye noxinano oluphezulu. Ukusetyenziswa kwazo kwizixhobo ze-microwave radio frequency, ii-LED, ii-laser, izixhobo zamandla kunye nezinye iindawo zitsale ingqalelo enkulu, kwaye zibonise amathuba ophuhliso olubanzi kunxibelelwano oluphathwayo, iigridi ezikrelekrele, uthutho lwesitimela, izithuthi zamandla amatsha, ii-elektroniki zabathengi, kunye nezixhobo zokukhanya ze-ultraviolet kunye neblue-green [1].
Umthombo womfanekiso: CASA, iZheshang Securities Research Institute
Umfanekiso 1 Isikali sexesha lesixhobo samandla seGaN kunye noqikelelo
Ulwakhiwo lwezinto ze-II GaN kunye neempawu
I-GaN yi-bandgap semiconductor ethe ngqo. Ububanzi be-bandgap yesakhiwo se-wurtzite kubushushu begumbi bumalunga ne-3.26eV. Izinto ze-GaN zinezakhiwo ezintathu eziphambili zekristale, ezizezi: isakhiwo se-wurtzite, isakhiwo se-sphalerite kunye nesakhiwo setyuwa yamatye. Phakathi kwazo, isakhiwo se-wurtzite sesona sakhiwo sekristale sizinzileyo. Umfanekiso 2 ngumzobo wesakhiwo se-wurtzite esinamahexagonal se-GaN. Isakhiwo se-wurtzite sezinto ze-GaN sisesakhiwo esixineneyo esinamahexagonal. Iseli nganye yeyunithi ineeathom ezili-12, kuquka iiathom ze-N ezi-6 kunye neeathom ze-Ga ezi-6. Iathom nganye ye-Ga (N) yenza ikhonkco kunye neeathom ze-N (Ga) ezi-4 ezikufutshane kwaye zibekwe ngokulandelelana kwe-ABABAB… kwicala [0001] [2].
Umfanekiso 2 Isakhiwo seWurtzite umzobo weseli yekristale yeGaN
III Ii-substrates ezisetyenziswa rhoqo kwi-GaN epitaxy
Kubonakala ngathi i-epitaxy efanayo kwi-GaN substrates yeyona ndlela ilungileyo kwi-GaN epitaxy. Nangona kunjalo, ngenxa yamandla amakhulu e-bond ye-GaN, xa ubushushu bufikelela kwinqanaba lokunyibilika le-2500℃, uxinzelelo lwayo lokubola oluhambelanayo lumalunga ne-4.5GPa. Xa uxinzelelo lokubola luphantsi kunolu xinzelelo, i-GaN ayinyibiliki kodwa ibola ngokuthe ngqo. Oku kwenza ubuchwepheshe bokulungiselela i-substrate evuthiweyo efana nendlela yeCzochralski ingafaneleki ukulungiselela i-GaN single crystal substrates, okwenza i-GaN substrates ibe nzima ukuyivelisa ngobuninzi kwaye ibiza kakhulu. Ke ngoko, i-substrates ezisetyenziswa rhoqo ekukhuleni kwe-GaN epitaxial ikakhulu yi-Si, SiC, isafire, njl. [3].
Itshathi 3 iGaN kunye neeparameter zezinto ezisetyenziswa rhoqo ze-substrate
I-GaN epitaxy kwi-sapphire
I-Sapphire ineempawu zeekhemikhali ezizinzileyo, ingabizi kakhulu, kwaye ikhula kakhulu kushishino olukhulu lwemveliso. Ke ngoko, iye yaba yenye yezona zinto zokuqala nezisetyenziswa kakhulu kwi-substrate engineering yezixhobo ze-semiconductor. Njengenye ye-substrate ezisetyenziswa kakhulu kwi-GaN epitaxy, iingxaki eziphambili ekufuneka zisonjululwe kwi-sapphire substrates zezi:
✔ Ngenxa yokungafani okukhulu kwelattice phakathi kwesafire (Al2O3) kunye neGaN (malunga ne-15%), uxinano olungalunganga kwindawo ephakathi komaleko we-epitaxial kunye ne-substrate luphezulu kakhulu. Ukuze kuncitshiswe iziphumo zalo ezimbi, i-substrate kufuneka iphathwe ngendlela enzima ngaphambi kokuba inkqubo ye-epitaxy iqale. Ngaphambi kokuba kukhuliswe i-epitaxy ye-GaN kwi-substrates zesafire, umphezulu we-substrate kufuneka uqale ucocwe ngokungqongqo ukuze kususwe ukungcola, umonakalo oshiyekileyo wokupholisha, njl.njl., kwaye kuveliswe izakhiwo zamanyathelo kunye nezitebhisi. Emva koko, umphezulu we-substrate uxutywe nge-nitride ukuze kutshintshwe iipropati zokumanzisa komaleko we-epitaxial. Okokugqibela, umaleko omncinci we-AlN buffer (odla ngokuba yi-10-100nm ubukhulu) kufuneka ubekwe kumphezulu we-substrate kwaye ufakwe kubushushu obuphantsi ukulungiselela ukukhula kokugqibela kwe-epitaxial. Nangona kunjalo, uxinano oluphezulu lwe-dislocation kwiifilimu ze-GaN epitaxial ezikhuliswe kwi-sapphire substrates lusephezulu kunolo lweefilimu ze-homoepitaxial (malunga ne-1010cm-2, xa kuthelekiswa noxinano oluphezulu lwe-zero dislocation kwiifilimu ze-silicon homoepitaxial okanye iifilimu ze-gallium arsenide homoepitaxial, okanye phakathi kwe-102 kunye ne-104cm-2). Uxinano oluphezulu lwe-defect lunciphisa ukuhamba kwe-carrier, ngaloo ndlela lunciphisa ubomi be-carrier encinci kwaye lunciphise ukuhanjiswa kobushushu, konke oku kuya kunciphisa ukusebenza kwesixhobo [4];
✔ I-coefficient yokwandiswa kobushushu be-sapphire inkulu kune-GaN, ngoko ke uxinzelelo lwe-biaxial compressive luya kuveliswa kumaleko we-epitaxial ngexesha lenkqubo yokuphola ukusuka kubushushu bokufaka ukuya kubushushu begumbi. Kwiifilimu ze-epitaxial ezijiyileyo, olu xinzelelo lunokubangela ukuqhekeka kwefilimu okanye ne-substrate;
✔ Xa kuthelekiswa nezinye izinto ezisetyenziswa kwi-substrates, umbane ohamba kwi-thermal we-sapphire substrates uphantsi (malunga ne-0.25W*cm-1*K-1 kwi-100℃), kwaye ukusebenza kokusasazwa kobushushu kuphantsi;
✔ Ngenxa yokuba ayiqhubi kakuhle, ii-sapphire substrates azilungele ukuhlanganiswa kwazo kunye nokusetyenziswa kwazo nezinye izixhobo ze-semiconductor.
Nangona uxinano lwee-GaN epitaxial layers ezikhuliswe kwi-sapphire substrates luphezulu, akubonakali ngathi kunciphisa kakhulu ukusebenza kwe-optoelectronic kwee-GaN-based blue-green LEDs, ngoko ke ii-sapphire substrates zisasetyenziswa kakhulu kwi-GaN-based LEDs.
Ngophuhliso lwezicelo ezintsha zezixhobo zeGaN ezifana neelaser okanye ezinye izixhobo zamandla ezinoxinano olukhulu, iziphene ezikhoyo ze-sapphire substrates ziye zaba ngumqobo ekusetyenzisweni kwazo. Ukongeza, ngophuhliso lwetekhnoloji yokukhula kwe-SiC substrate, ukunciphisa iindleko kunye nokuvuthwa kwetekhnoloji ye-GaN epitaxial kwi-Si substrates, uphando olongezelelweyo malunga nokukhulisa iileya ze-GaN epitaxial kwi-sapphire substrates luye lwabonisa kancinci kancinci indlela yokuphola.
I-GaN epitaxy kwi-SiC
Xa kuthelekiswa nesafire, ii-substrates zeSiC (iikristale ze-4H- kunye ne-6H) zinokungalingani okuncinci kwelatisi kunye nee-GaN epitaxial layers (3.1%, ezilingana neefilimu ze-epitaxial ezijolise kwi-[0001], i-conductivity ephezulu yobushushu (malunga ne-3.8W*cm-1*K-1), njl. Ukongeza, i-conductivity yee-substrates zeSiC ikwavumela ukuba kwenziwe uqhagamshelwano lombane ngasemva kwe-substrate, nto leyo enceda ukwenza lula ulwakhiwo lwesixhobo. Ukubakho kwezi zibonelelo kuye kwatsala abaphandi abaninzi ukuba basebenze kwi-GaN epitaxy kwii-substrates ze-silicon carbide.
Nangona kunjalo, ukusebenza ngokuthe ngqo kwi-SiC substrates ukuze uphephe ukukhulisa ii-GaN epilayers kukwajongene noluhlu lwezinto ezingalunganga, kuquka oku kulandelayo:
✔ Uburhabaxa bomphezulu we-SiC substrates buphezulu kakhulu kunobo be-sapphire substrates (uburhabaxa be-sapphire 0.1nm RMS, uburhabaxa be-SiC 1nm RMS), ii-SiC substrates zinobunzima obuphezulu kunye nokusebenza kakubi kokucubungula, kwaye obu burhabaxa kunye nomonakalo oshiyekileyo wokupholisha nazo zezinye zezona zizathu zeziphene kwi-GaN epilayers.
✔ Uxinano lwe-screw dislocation lwe-SiC substrates luphezulu (uxinano lwe-dislocation yi-103-104cm-2), i-screw dislocations inokusasaza iye kwi-GaN epilayer kwaye inciphise ukusebenza kwesixhobo;
✔ Ulungiselelo lweathomu kumphezulu we-substrate lubangela ukwakheka kweempazamo zokubeka (ii-BSF) kwi-epilayer ye-GaN. Kwi-epitaxial GaN kwi-substrates ze-SiC, kukho imiyalelo emininzi yolungiselelo lweathomu kwi-substrate, nto leyo ebangela ukuba ulungelelwano lokuqala lwe-athomu lokubeka i-epitaxial GaN kumaleko wayo, olunokuthambekela kwiimpazamo zokubeka i-stacking. Iimpazamo zokubeka i-stacking (ii-SF) zizisa amasimi ombane akhelwe ngaphakathi ecaleni kwe-c-axis, nto leyo ekhokelela kwiingxaki ezifana nokuvuza kwezixhobo zokwahlula abathwali beenqwelo-moya;
✔ I-coefficient yokwandiswa kobushushu be-substrate ye-SiC incinci kune-AlN kunye ne-GaN, ebangela ukuqokelelwa koxinzelelo lobushushu phakathi komaleko we-epitaxial kunye ne-substrate ngexesha lenkqubo yokupholisa. UWaltereit noBrand baqikelele ngokusekelwe kwiziphumo zabo zophando ukuba le ngxaki inokupheliswa okanye isonjululwe ngokukhulisa amaleko e-epitaxial eGaN kwi-alN nucleation layers ezibhityileyo nezixineneyo;
✔ Ingxaki yokungamanzi kakuhle kweeathom zeGa. Xa kukhuliswa iileya zeGaN epitaxial ngqo kumphezulu weSiC, ngenxa yokungamanzi kakuhle phakathi kweeathom ezimbini, iGaN ithambekele ekukhuleni kwesiqithi se-3D kumphezulu we-substrate. Ukwazisa umaleko we-buffer sesona sisombululo sisetyenziswa kakhulu ukuphucula umgangatho wezinto ze-epitaxial kwi-epitaxy yeGaN. Ukwazisa umaleko we-buffer we-AlN okanye we-AlxGa1-xN kunokuphucula ngempumelelo ukumanzi komphezulu weSiC kwaye kwenze umaleko we-epitaxial weGaN ukhule ngeendlela ezimbini. Ukongeza, inokulawula uxinzelelo kwaye ithintele iziphene ze-substrate ukuba zinganwenwi kwi-epitaxy yeGaN;
✔ Itekhnoloji yokulungiselela ii-substrates zeSiC ayivuthwanga, ixabiso le-substrate liphezulu, kwaye bambalwa ababoneleli kwaye bambalwa ababoneleli.
Uphando lukaTorres nabanye lubonisa ukuba ukugrumba i-substrate yeSiC nge-H2 kubushushu obuphezulu (1600°C) ngaphambi kwe-epitaxy kunokuvelisa isakhiwo esicwangcisiweyo ngakumbi kumphezulu we-substrate, ngaloo ndlela kufumaneke ifilimu ye-AlN epitaxial esemgangathweni ophezulu kunaxa ikhuliswe ngqo kumphezulu we-substrate yokuqala. Uphando lukaXie kunye neqela lakhe lukwabonisa ukuba ukugrumba kwangaphambili kwe-substrate ye-silicon carbide kunokuphucula kakhulu imo yomhlaba kunye nomgangatho wekristale womaleko we-GaN epitaxial. USmith nabanye bafumanise ukuba ukuqhekeka kwemisonto okuvela kumaleko we-substrate/buffer kunye ne-buffer layer/epitaxial layer interfaces kunxulumene nokuthamba kwe-substrate [5].
Umfanekiso 4 Imo yeTEM yeesampuli ze-GaN epitaxial layer ezikhuliswe kwi-6H-SiC substrate (0001) phantsi kweemeko ezahlukeneyo zonyango lomphezulu (a) ukucoca ngamakhemikhali; (b) ukucoca ngamakhemikhali + unyango lwe-hydrogen plasma; (c) ukucoca ngamakhemikhali + unyango lwe-hydrogen plasma + unyango lobushushu be-hydrogen lwe-1300℃ imizuzu engama-30
I-GaN epitaxy kwi-Si
Xa kuthelekiswa ne-silicon carbide, i-sapphire kunye nezinye izinto ezisetyenziswa kwi-substrates, inkqubo yokulungiselela i-silicon substrate ivuthiwe, kwaye inokubonelela ngokuzinzileyo ngezinto ezisetyenziswa kwi-substrates ezinkulu ezivuthiweyo ezinexabiso eliphezulu. Kwangaxeshanye, ukuhanjiswa kobushushu kunye nokuhanjiswa kombane kulungile, kwaye inkqubo yesixhobo se-elektroniki se-Si ivuthiwe. Amathuba okudibanisa ngokugqibeleleyo izixhobo ze-optoelectronic GaN kunye nezixhobo ze-elektroniki ze-Si kwixesha elizayo nako kwenza ukukhula kwe-GaN epitaxy kwi-silicon kube nomtsalane kakhulu.
Nangona kunjalo, ngenxa yomahluko omkhulu kwii-lattice constants phakathi kwe-Si substrate kunye nezinto ze-GaN, i-epitaxy eyahlukileyo ye-GaN kwi-Si substrate yi-epitaxy eqhelekileyo yokungafani okukhulu, kwaye ikwafuna ukujongana nothotho lweengxaki:
✔ Ingxaki yamandla ojongano lomphezulu. Xa iGaN ikhula kwi-substrate yeSi, umphezulu we-substrate yeSi uya kuqala ufakwe i-nitride ukuze wenze umaleko we-silicon nitride ongaguqukiyo ongalungelaniyo nokukhula kwe-GaN enoxinano oluphezulu. Ukongeza, umphezulu weSi uya kuqala uqhagamshelane neGa, eya konakalisa umphezulu we-substrate yeSi. Kumaqondo obushushu aphezulu, ukubola komphezulu weSi kuya kusasazeka kwi-GaN epitaxial layer ukuze kwenziwe amabala e-silicon amnyama.
✔ Ukungalingani okungaguqukiyo kwe-lattice phakathi kwe-GaN kunye ne-Si kukhulu (~17%), okuya kukhokelela ekwakhiweni kwe-high-density threading dislocations kwaye kunciphise kakhulu umgangatho we-epitaxial layer;
✔ Xa kuthelekiswa neSi, iGaN inomlinganiselo omkhulu wokwandisa ubushushu (umlinganiselo wokwandisa ubushushu weGaN umalunga ne-5.6×10-6K-1, umlinganiselo wokwandisa ubushushu weSi umalunga ne-2.6×10-6K-1), kwaye iintanda zinokuveliswa kumaleko weGaN epitaxial ngexesha lokuphola kobushushu be-epitaxial ukuya kubushushu begumbi;
✔ I-Si isabela kwi-NH3 kumaqondo obushushu aphezulu ukuze yenze i-polycrystalline SiNx. I-AlN ayinakwenza i-nucleus ejolise ngokukhethekileyo kwi-polycrystalline SiNx, nto leyo ekhokelela ekungahambelani kakuhle komaleko we-GaN okhule kamva kunye nenani elikhulu leziphene, nto leyo ebangela umgangatho ophantsi wekristale komaleko we-GaN epitaxial, kwanobunzima bokwenza umaleko we-GaN epitaxial one-crystalline [6].
Ukuze kusonjululwe ingxaki yokungafani okukhulu kwelathisi, abaphandi bazame ukungenisa izinto ezifana ne-AlAs, i-GaAs, i-AlN, i-GaN, i-ZnO, kunye ne-SiC njengeeleya ze-buffer kwi-substrates ze-Si. Ukuze kuthintelwe ukwenziwa kwe-polycrystalline SiNx kunye nokunciphisa iziphumo zayo ezimbi kumgangatho wekristale wezinto ze-GaN/AlN/Si (111), i-TMAl idla ngokufuneka ukuba ingeniswe ixesha elithile ngaphambi kokukhula kwe-epitaxial kweleya ye-AlN buffer ukuthintela i-NH3 ukuba ingasabelani nomphezulu we-Si oveziweyo ukuze kwenziwe i-SiNx. Ukongeza, iiteknoloji ze-epitaxial ezifana netekhnoloji ye-substrate enepateni zingasetyenziselwa ukuphucula umgangatho weleya ye-epitaxial. Uphuhliso lwezi teknoloji lunceda ukuthintela ukwakheka kwe-SiNx kwi-interface ye-epitaxial, ukukhuthaza ukukhula okunemilinganiselo emibini kweleya ye-GaN epitaxial, kunye nokuphucula umgangatho wokukhula kweleya ye-epitaxial. Ukongeza, ileya ye-AlN buffer ingeniswa ukuze ihlawule uxinzelelo lokuxinana olubangelwa ngumahluko kwii-coefficients zokwandiswa kobushushu ukuze kuthintelwe ukuqhekeka kwileya ye-GaN epitaxial kwi-substrate ye-silicon. Uphando lukaKrost lubonisa ukuba kukho ulwalamano oluhle phakathi kobukhulu beleyara ye-AlN buffer kunye nokunciphisa uxinzelelo. Xa ubukhulu beleyara ye-buffer bufikelela kwi-12nm, ileyara ye-epitaxial enobukhulu obungaphezulu kwe-6μm ingakhuliswa kwi-silicon substrate ngokusebenzisa i-scheme efanelekileyo yokukhula ngaphandle kokuqhekeka kweleyara ye-epitaxial.
Emva kwemizamo yexesha elide yabaphandi, umgangatho wee-GaN epitaxial layers ezikhuliswe kwi-silicon substrates uphuculwe kakhulu, kwaye izixhobo ezifana nee-field effect transistors, ii-Schottky barrier ultraviolet detectors, ii-LED eziluhlaza okwesibhakabhaka kunye nee-ultraviolet lasers zenze inkqubela phambili enkulu.
Ngamafutshane, ekubeni ii-substrates ze-GaN epitaxial ezisetyenziswa rhoqo ziyi-epitaxy eyahlukileyo, zonke zijongene neengxaki ezifanayo ezifana nokungafani kwe-lattice kunye nomahluko omkhulu kwi-thermal expansion coefficients ukuya kumanqanaba ahlukeneyo. Ii-substrates ze-epitaxial GaN ezifanayo zinqunyelwe kukuvuthwa kwetekhnoloji, kwaye ii-substrates azikaveliswa ngobuninzi. Iindleko zemveliso ziphezulu, ubungakanani be-substrate buncinci, kwaye umgangatho we-substrate awulungile. Uphuhliso lwee-substrates ezintsha ze-GaN epitaxial kunye nokuphuculwa komgangatho we-epitaxial kuseyenye yezinto ezibalulekileyo ezithintela uphuhliso oluqhubekayo lweshishini le-epitaxial le-GaN.
IV. Iindlela eziqhelekileyo ze-GaN epitaxy
I-MOCVD (ukufakwa komphunga weekhemikhali)
Kubonakala ngathi i-epitaxy efanayo kwi-GaN substrates yeyona ndlela ilungileyo kwi-epitaxy ye-GaN. Nangona kunjalo, ekubeni izinto ezibangela ukuba kubekho umphunga wekhemikhali yi-trimethylgallium kunye ne-ammonia, kwaye igesi ethwalayo yi-hydrogen, ubushushu obuqhelekileyo bokukhula kwe-MOCVD bumalunga ne-1000-1100℃, kwaye izinga lokukhula kwe-MOCVD limalunga nee-microns ezimbalwa ngeyure. Ingavelisa ii-interfaces ezinde kwinqanaba le-athomu, ezifanelekileyo kakhulu ekukhuleni kwe-heterojunctions, ii-quantum wells, ii-superlattices kunye nezinye izakhiwo. Izinga layo lokukhula ngokukhawuleza, ukufana okuhle, kunye nokufaneleka kokukhula kwendawo enkulu kunye neenxalenye ezininzi zihlala zisetyenziswa kwimveliso yemizi-mveliso.
I-MBE (i-molecular beam epitaxy)
Kwi-molecular beam epitaxy, iGa isebenzisa umthombo we-elemental, kwaye i-nitrogen esebenzayo ifunyanwa kwi-nitrogen nge-RF plasma. Xa kuthelekiswa nendlela ye-MOCVD, ubushushu bokukhula kwe-MBE buphantsi malunga ne-350-400℃. Ubushushu bokukhula obuphantsi bunokuthintela ungcoliseko oluthile olunokubangelwa ziindawo ezinobushushu obuphezulu. Inkqubo ye-MBE isebenza phantsi kwe-vacuum ephezulu kakhulu, evumela ukuba idibanise iindlela ezininzi zokufumanisa kwindawo. Kwangaxeshanye, izinga layo lokukhula kunye namandla emveliso azinakuthelekiswa ne-MOCVD, kwaye isetyenziswa ngakumbi kuphando lwesayensi [7].
Umfanekiso 5 (a) Eiko-MBE schematic (b) MBE main reaction chamber schematic
Indlela ye-HVPE (i-hydride vapor phase epitaxy)
Izinto ezandulela indlela ye-hydride vapor phase epitaxy yiGaCl3 kunye neNH3. UDetchprohm nabanye basebenzise le ndlela ukukhulisa umaleko we-epitaxial we-GaN onama-microns amaninzi phezu komphezulu we-sapphire substrate. Kuvavanyo lwabo, umaleko we-ZnO ukhuliswe phakathi kwe-sapphire substrate kunye nomaleko we-epitaxial njengomaleko we-buffer, kwaye umaleko we-epitaxial wasuswa kumphezulu we-sapphire. Xa kuthelekiswa ne-MOCVD kunye ne-MBE, uphawu oluphambili lwendlela ye-HVPE lizinga layo eliphezulu lokukhula, elifanelekileyo kwimveliso yamaleko amakhulu kunye nezinto ezininzi. Nangona kunjalo, xa ubukhulu bomaleko we-epitaxial budlula i-20μm, umaleko we-epitaxial oveliswa yile ndlela unokuba neentanda.
I-Akira USUI yazisa itekhnoloji ye-substrate enepateni esekelwe kule ndlela. Baqale bakhulisa umaleko omncinci we-GaN epitaxial onobukhulu obuyi-1-1.5μm kwi-substrate yesafire besebenzisa indlela ye-MOCVD. Umaleko we-epitaxial wawunomaleko we-GaN buffer onobukhulu obuyi-20nm okhuliswe phantsi kweemeko zobushushu obuphantsi kunye nomaleko we-GaN okhuliswe phantsi kweemeko zobushushu obuphezulu. Emva koko, kwi-430℃, umaleko we-SiO2 wabekwa phezu komphezulu womaleko we-epitaxial, kwaye kwenziwa imicu yeefestile kwifilimu ye-SiO2 nge-photolithography. Isithuba semigca sasiyi-7μm kwaye ububanzi bemaski babuqala kwi-1μm ukuya kwi-4μm. Emva kolu phuculo, bafumana umaleko we-GaN epitaxial kwi-substrate yesafire enobubanzi obuyi-2 intshi eyayingenaziqhekeko kwaye igudile njengesipili nangona ubukhulu bunyuke baba ngamashumi okanye amakhulu ee-microns. Uxinano lwesiphako lwancitshiswa ukusuka kwi-109-1010cm-2 yendlela yesiqhelo ye-HVPE ukuya malunga ne-6×107cm-2. Bakwabonise kolu vavanyo ukuba xa izinga lokukhula lidlula i-75μm/h, umphezulu wesampuli uya kuba rhabaxa [8].
Umfanekiso 6 Isicwangciso seMifanekiso yeSubstrate yeMizobo
V. Isishwankathelo kunye neMbono
Izixhobo zeGaN zaqala ukuvela ngo-2014 xa i-LED yesibane esiluhlaza okwesibhakabhaka yaphumelela iMbasa yeNobel kwiFiziksi ngaloo nyaka, yaza yangena kwicandelo loluntu lezicelo zokutshaja ngokukhawuleza kwicandelo le-elektroniki yabathengi. Enyanisweni, izicelo kwizixhobo zokukhulisa amandla kunye nezixhobo zeRF ezisetyenziswa kwizikhululo zesiseko ze-5G uninzi lwabantu abangaziboniyo nazo ziye zavela ngokuzolileyo. Kwiminyaka yakutshanje, ukuphumelela kwezixhobo zamandla ezisebenzisa iimoto ezisekelwe kwiGaN kulindeleke ukuba kuvule iindawo ezintsha zokukhula kwimarike yezicelo zezinto zeGaN.
Imfuno enkulu yemarike ngokuqinisekileyo iya kukhuthaza uphuhliso lwamashishini kunye netekhnoloji ezinxulumene neGaN. Ngokukhula kunye nokuphuculwa kwekhonkco lemizi-mveliso ezinxulumene neGaN, iingxaki ezijongene netekhnoloji yangoku ye-epitaxial yeGaN ekugqibeleni ziya kuphuculwa okanye zoyiswe. Kwixesha elizayo, ngokuqinisekileyo abantu baya kuphuhlisa iitekhnoloji ezintsha ze-epitaxial kunye neendlela ezibalaseleyo ze-substrate. Ngelo xesha, abantu baya kuba nakho ukukhetha itekhnoloji yophando lwangaphandle efanelekileyo kunye ne-substrate kwiimeko ezahlukeneyo zesicelo ngokweempawu zeemeko zesicelo, kwaye bavelise iimveliso ezenziwe ngokwezifiso ezikhuphisanayo kakhulu.
Ixesha leposi: Juni-28-2024