1. ʻEkolu-hanauna semiconductor
Ua hoʻomohala ʻia ka ʻenehana semiconductor mua ma muli o nā mea semiconductor e like me Si a me Ge. ʻO ia ke kumu waiwai no ka hoʻomohala ʻana i nā transistors a me ka ʻenehana kaapuni hoʻohui. ʻO nā mea hana semiconductor mua i hoʻokumu i ke kumu no ka ʻoihana uila i ke kenekulia 20 a ʻo ia nā mea kumu no ka ʻenehana kaapuni hoʻohui.
ʻO nā mea semiconductor lua o ka hanauna he nui ka gallium arsenide, indium phosphide, gallium phosphide, indium arsenide, alumini arsenide a me kā lākou mau pūhui ternary. ʻO nā mea semiconductor lua o ka hanauna ke kumu o ka ʻoihana ʻike optoelectronic. Ma kēia kumu, ua hoʻomohala ʻia nā ʻoihana pili e like me ke kukui, hōʻike, laser, a me nā photovoltaics. Hoʻohana nui ʻia lākou i ka ʻenehana ʻike hou a me nā ʻoihana hōʻike optoelectronic.
ʻO nā mea ʻelele o nā mea semiconductor ʻekolu o nā hanauna he gallium nitride a me ka carbide silicon. Ma muli o ko lākou ākea ākea, kiʻekiʻe electron saturation drift velocity, kiʻekiʻe thermal conductivity, a kiʻekiʻe breakdown ikaika kahua, he mau mea kūpono lākou no ka hoʻomākaukau ʻana i ka mana kiʻekiʻe, kiʻekiʻe-frequency, a me nā mea uila haʻahaʻa. Ma waena o lākou, loaʻa i nā mea mana silicon carbide ka maikaʻi o ke kiʻekiʻe o ka ikehu kiʻekiʻe, ka haʻahaʻa haʻahaʻa o ka ikehu, a me ka liʻiliʻi liʻiliʻi, a loaʻa nā manaʻo ākea ākea i nā kaʻa ikehu hou, photovoltaics, kaʻa kaʻaahi, ʻikepili nui, a me nā māla ʻē aʻe. Loaʻa i nā polokalamu RF Gallium nitride nā pono o ke alapine kiʻekiʻe, ka mana kiʻekiʻe, ka bandwidth ākea, ka hoʻohana haʻahaʻa haʻahaʻa a me ka liʻiliʻi liʻiliʻi, a loaʻa nā manaʻo noi ākea i nā kamaʻilio 5G, ka Internet of Things, radar pūʻali a me nā kahua ʻē aʻe. Eia kekahi, ua hoʻohana nui ʻia nā mea mana o ka gallium nitride ma ke kahua haʻahaʻa haʻahaʻa. Eia kekahi, i nā makahiki i hala iho nei, manaʻo ʻia nā mea e puka mai ana i ka gallium oxide e hoʻohui i ka ʻenehana me nā ʻenehana SiC a me GaN i loaʻa, a loaʻa iā ia nā manaʻo noi i nā kula haʻahaʻa haʻahaʻa a kiʻekiʻe.
Ke hoʻohālikelike ʻia me nā mea semiconductor lua-hanau, ʻoi aku ka laulā o nā mea semiconductor o ke kolu o ka hanauna (ka laulā bandgap o Si, kahi mea maʻamau o ka mea semiconductor hanauna mua, ma kahi o 1.1eV, ka laulā bandgap o GaAs, kahi maʻamau. mea o ka lua o ka hanauna semiconductor mea, ma kahi o 1.42eV, a me ka bandgap laula o ʻO GaN, kahi mea maʻamau o ke kolu o ka hanauna semiconductor material, ʻoi aku ma luna o 2.3eV), ʻoi aku ka ikaika o ka pale ʻana i ka radiation, ʻoi aku ka ikaika o ka pale ʻana i ka haki ʻana o ke kahua uila, a me ke kūpaʻa wela kiʻekiʻe. ʻO nā mea hana semiconductor ʻekolu o ka hanauna me ka laulā bandgap ākea e kūpono loa no ka hana ʻana i nā mea uila uila-kūʻai, kiʻekiʻe-frequency, mana kiʻekiʻe a me ka hoʻohui kiʻekiʻe. ʻO kā lākou mau noi i nā mīkini uila uila microwave, nā LED, nā lasers, nā mana mana a me nā kahua ʻē aʻe ua hoʻohuli nui ʻia, a ua hōʻike lākou i nā manaʻo hoʻomohala ākea i nā kamaʻilio kelepona, nā grids akamai, ka transit rail, nā kaʻa ikehu hou, nā mea uila uila, a me ka ultraviolet a me ka uliuli. - nā lako kukui ʻōmaʻomaʻo [1].
Puna kiʻi: CASA, Zheshang Securities Research Institute
Kiʻi 1 GaN ka nui manawa a me ka wānana
II GaN mea a me na ano
ʻO GaN kahi semiconductor bandgap pololei. ʻO ka laulā bandgap o ka hale wurtzite ma ka lumi wela ma kahi o 3.26eV. Loaʻa i nā mea GaN ʻekolu mau hale aniani nui, ʻo ia ka wurtzite structure, sphalerite structure a me ka pōhaku paʻakai. I waena o lākou, ʻo ka ʻōnaehana wurtzite ka hale aniani paʻa loa. He kiʻi 2 ka kiʻi o ka hanana wurtzite hexagonal o GaN. ʻO ke ʻano wurtzite o ka mea GaN no kahi hale hexagonal kokoke i hoʻopili ʻia. He 12 mau ʻātoma ko kēlā me kēia pūnaewele, me 6 N nā mana a me 6 Ga nā mana. Hoʻokumu kēlā me kēia ʻātoma Ga (N) i mea paʻa me nā ʻātoma N (Ga) kokoke loa 4 a hoʻopaʻa ʻia ma ke kaʻina o AABAB… ma ke ala [0001] [2].
Kiʻi 2 Wurtzite hoʻolālā GaN kiʻi pahu aniani
III Nā pani hoʻohana maʻamau no ka epitaxy GaN
Me he mea lā ʻo ka epitaxy homogeneous ma nā substrates GaN ke koho maikaʻi loa no ka epitaxy GaN. Eia nō naʻe, ma muli o ka ikehu paʻa nui o GaN, ke hiki ka mahana i ka helu heheʻe o 2500 ℃, ʻo kona kaomi decomposition pili e pili ana i 4.5GPa. Ke emi iho ke kaomi decomposition ma mua o kēia kaomi, ʻaʻole hehee ʻo GaN akā decompose pololei. ʻAʻole kūpono kēia i nā ʻenehana hoʻomākaukau substrate e like me ke ʻano Czochralski no ka hoʻomākaukau ʻana i nā substrates kristal hoʻokahi GaN, e paʻakikī ai nā substrates GaN i ka hana nui a me ke kumu kūʻai. No laila, ʻo nā substrate i hoʻohana mau ʻia i ka ulu ʻana o ka epitaxial GaN ʻo ia ka nui o Si, SiC, sapphire, etc. [3].
Palapala 3 GaN a me nā ʻāpana o nā mea hoʻohana maʻamau
GaN epitaxy ma ka sapphire
Loaʻa i ka Sapphire nā waiwai kemika paʻa, maʻalahi, a he kiʻekiʻe kiʻekiʻe o ka ʻoihana hana nui. No laila, ua lilo ia i mea hoʻohana mua loa a hoʻohana nui ʻia i ka ʻenehana mīkini semiconductor. Ma ke ʻano he mea hoʻohana maʻamau no ka epitaxy GaN, ʻo nā pilikia nui e pono e hoʻoponopono ʻia no nā substrates sapphire:
✔ Ma muli o ka nui o ka lattice mismatch ma waena o ka sapphire (Al2O3) a me ka GaN (ma kahi o 15%), ʻoi loa ke kiʻekiʻe o ka defect density ma ke kikowaena ma waena o ka papa epitaxial a me ka substrate. I mea e hōʻemi ai i kona hopena ʻino, pono e kau ʻia ka substrate i ka pretreatment paʻakikī ma mua o ka hoʻomaka ʻana o ka hana epitaxy. Ma mua o ka ulu ʻana o GaN epitaxy ma luna o nā substrate sapphire, pono e hoʻomaʻemaʻe mua ʻia ka ʻili o ka substrate e wehe i nā mea haumia, koena pohō pohō, a me nā mea ʻē aʻe, a no ka hana ʻana i nā ʻanuʻu a me nā hana ʻili. A laila, ua nitrided ka ʻili substrate e hoʻololi i nā waiwai pulu o ka papa epitaxial. ʻO ka mea hope loa, pono e waiho ʻia kahi ʻāpana paʻa paʻa AlN (maʻamau 10-100nm mānoanoa) ma ka ʻili o ka substrate a hoʻopili ʻia i ka wela haʻahaʻa e hoʻomākaukau ai no ka ulu ʻana o ka epitaxial hope. ʻOiaʻiʻo, ʻoi aku ka kiʻekiʻe o ka dislocation ma nā kiʻi ʻoniʻoni epitaxial GaN i ulu ʻia ma nā substrate sapphire ma mua o nā kiʻi ʻoniʻoni homepitaxial (e pili ana i 1010cm-2, i hoʻohālikelike ʻia me nā kiʻiʻoniʻoni homoepitaxial silicon a i ʻole nā kiʻi ʻoniʻoni homoepitaxial gallium arsenide, a i ʻole ma waena o 102 a me 104cm- 2). ʻO ke kiʻekiʻe kiʻekiʻe o ka defect density e hōʻemi ana i ka neʻe ʻana o ka mea lawe, ma laila e hoʻopōkole ai i ke ola o ka mea lawe liʻiliʻi a hōʻemi i ka conductivity thermal, nā mea a pau e hōʻemi i ka hana o ka mīkini [4];
✔ ʻOi aku ka nui o ka nui o ka hoʻonui wela o ka sapphire ma mua o ko GaN, no laila e hoʻokumu ʻia ke koʻikoʻi biaxial compressive i ka papa epitaxial i ka wā o ka hoʻomaha ʻana mai ka wela deposition a i ka mahana lumi. No nā kiʻiʻoniʻoni epitaxial mānoanoa, hiki i kēia koʻikoʻi ke kumu i ka haki ʻana o ke kiʻiʻoniʻoni a i ʻole ka substrate;
✔ Ke hoʻohālikelike ʻia me nā substrates ʻē aʻe, ʻoi aku ka haʻahaʻa o ka conductivity thermal o nā substrates sapphire (e pili ana i 0.25W * cm-1 * K-1 ma 100 ℃), a maikaʻi ʻole ka hana ʻana o ka wela;
✔ Ma muli o kona conductivity maikaʻi ʻole, ʻaʻole kūpono nā substrate sapphire i kā lākou hoʻohui ʻana a me ka noi ʻana me nā mea semiconductor ʻē aʻe.
ʻOiai he kiʻekiʻe ka nui o nā hemahema o nā papa epitaxial GaN i ulu ma luna o nā substrate sapphire, ʻaʻole ia e hōʻemi nui i ka hana optoelectronic o nā LED polū-ʻōmaʻomaʻo GaN, no laila ua hoʻohana mau ʻia nā substrates sapphire i nā substrate no nā LED-based GaN.
Me ka hoʻomohala ʻana o nā noi hou aʻe o nā mea GaN e like me nā lasers a i ʻole nā mea mana kiʻekiʻe kiʻekiʻe, ua lilo nā hemahema o nā substrates sapphire i mea palena i kā lākou noi. Eia kekahi, me ka hoʻomohala ʻana o ka ʻenehana ulu ʻana o ka substrate SiC, ka hoʻemi ʻana i ke kumukūʻai a me ka oʻo ʻana o ka ʻenehana epitaxial GaN ma nā substrates Si, ʻoi aku ka nui o ka noiʻi e pili ana i ka ulu ʻana o nā papa epitaxial GaN ma nā substrate sapphire i hōʻike mālie i kahi ʻano hoʻomaha.
GaN epitaxy ma SiC
Hoʻohālikelike ʻia me ka sapphire, ʻo nā substrate SiC (4H- a me 6H-crystals) he liʻiliʻi liʻiliʻi liʻiliʻi liʻiliʻi me nā papa epitaxial GaN (3.1%, like me [0001] oriented epitaxial films), ʻoi aku ka nui o ka conductivity thermal (e pili ana i 3.8W*cm-1*K. -1), etc. Eia kekahi, hiki i ka conductivity o nā substrates SiC ke hiki ke hana i nā pilina uila ma ka hope o ka substrate, e kōkua ana i ka maʻalahi o ke ʻano o ka hāmeʻa. ʻO ka loaʻa ʻana o kēia mau mea maikaʻi ua hoʻowalewale i nā mea noiʻi hou aʻe e hana ma ka epitaxy GaN ma nā substrates carbide silika.
Eia nō naʻe, ʻo ka hana pololei ʻana i nā substrates SiC e pale aku i ka ulu ʻana o nā epilayers GaN e kū pū ana i kahi ʻano o nā hemahema, me kēia mau mea:
✔ ʻOi aku ka kiʻekiʻe o ka ʻili o nā substrates SiC ma mua o nā substrates sapphire (sapphire roughness 0.1nm RMS, SiC roughness 1nm RMS), ʻo nā substrate SiC he paʻakikī kiʻekiʻe a me ka maikaʻi ʻole o ka hana ʻana, a ʻo kēia ʻōpala a me ke koena o ka pōʻino polishing kekahi o nā nā kumu o nā hemahema i nā epilayers GaN.
✔ He kiʻekiʻe ke kiʻekiʻe o ka dislocation screw o nā substrate SiC (dislocation density 103-104cm-2), hiki ke hoʻolaha i nā dislocations screw i ka epilayer GaN a hōʻemi i ka hana o ka mea hana;
✔ ʻO ka hoʻonohonoho atomika ma ka ʻili o ka substrate e hoʻoulu i ka hoʻokumu ʻana i nā hewa hoʻopaʻa (BSF) i ka epilayer GaN. No ka epitaxial GaN ma ka SiC substrates, he nui nā kauoha hoʻonohonoho atomika ma luna o ka substrate, ka hopena o ke ʻano like ʻole o ka hoʻonohonoho hoʻonohonoho atomika mua o ka papa GaN epitaxial ma luna o ia mea, kahi i hiki ke hoʻopaʻa i nā hewa. Hoʻokomo ʻia nā hewa hoʻopaʻa ʻana (SFs) i kūkulu ʻia i loko o ka axis c, e alakaʻi ana i nā pilikia e like me ka leakage o nā mea hoʻokaʻawale i ka mokulele;
✔ ʻOi aku ka liʻiliʻi o ka helu hoʻonui wela o ka substrate SiC ma mua o ka AlN a me GaN, ka mea e hoʻoulu ai i ke koʻikoʻi wela ma waena o ka papa epitaxial a me ka substrate i ka wā o ka hoʻoilo. Ua wānana ʻo Waltereit lāua ʻo Brand ma muli o kā lākou mau hopena noiʻi e hiki ke hoʻopau ʻia kēia pilikia ma o ka ulu ʻana i nā papa epitaxial GaN ma luna o nā ʻāpana nucleation AlN i hoʻopaʻa ʻia;
✔ Ka pilikia o ka wettability maikaʻi ʻole o Ga atoms. Ke ulu pololei nei nā papa epitaxial GaN ma ka ʻili SiC, ma muli o ka maikaʻi ʻole o ka pulu ma waena o nā ʻātoma ʻelua, ua maʻalahi ʻo GaN i ka ulu ʻana o ka mokupuni 3D ma ka ʻili substrate. ʻO ka hoʻokomo ʻana i kahi papa pale ka hopena maʻamau i hoʻohana ʻia e hoʻomaikaʻi i ka maikaʻi o nā mea epitaxial ma GaN epitaxy. ʻO ka hoʻokomo ʻana i kahi papa pale AlN a i ʻole AlxGa1-xN hiki ke hoʻomaikaʻi maikaʻi i ka pulu o ka ʻili SiC a hoʻonui i ka papa epitaxial GaN i ʻelua mau ʻāpana. Eia kekahi, hiki iā ia ke hoʻoponopono i ke kaumaha a pale i nā hemahema substrate mai ka hoʻonui ʻana i ka epitaxy GaN;
✔ ʻO ka ʻenehana hoʻomākaukau o nā substrates SiC ʻaʻole i oʻo, kiʻekiʻe ke kumukūʻai substrate, a he liʻiliʻi nā mea hoʻolako a liʻiliʻi ka lako.
Hōʻike ka noiʻi a Torres et al. ʻo ke kālai ʻana i ka substrate SiC me ka H2 i ka wela kiʻekiʻe (1600°C) ma mua o ka hiki ʻana i ka epitaxy ke hoʻohua i kahi ʻano ʻanuʻu i kauoha ʻia ma ka ʻili o ka substrate, no laila e loaʻa ai kahi kiʻiʻoniʻoni epitaxial AlN ʻoi aku ka maikaʻi ma mua o ka wā pololei. ulu ʻia ma ka ʻili o ka substrate kumu. Ua hōʻike pū ʻia ka noiʻi a Xie a me kāna hui e hiki ke hoʻomaikaʻi maikaʻi i ka hoʻomaʻamaʻa mua ʻana o ka substrate silicon carbide i ka morphology o ka ʻili a me ka maikaʻi aniani o ka papa epitaxial GaN. Smith et al. Ua ʻike ʻia ʻo nā dislocations threading e puka mai ana mai ka substrate / buffer layer a me ka buffer layer / epitaxial layer interfaces pili i ka palahalaha o ka substrate [5].
Kiʻi 4 TEM morphology o GaN epitaxial layer samples i ulu ma 6H-SiC substrate (0001) ma lalo o nā kūlana lapaʻau like ʻole (a) hoʻomaʻemaʻe kemika; (b) ka hoʻomaʻemaʻe kemika + ka mālama ʻana i ka plasma hydrogen; (c) hoʻomaʻemaʻe kemika + hoʻomaʻamaʻa hydrogen plasma + 1300 ℃ ka mālama wela hydrogen no 30min
GaN epitaxy ma Si
Ke hoʻohālikelike ʻia me ka silicon carbide, sapphire a me nā substrates ʻē aʻe, ʻo ke kaʻina hana hoʻomākaukau substrate silicon ua oʻo, a hiki iā ia ke hoʻolako paʻa i nā substrates nui-nui me ka hana kiʻekiʻe. Ma ka manawa like, maikaʻi ka conductivity thermal a me ka conductivity uila, a ʻo ke kaʻina hana uila ʻo Si ua oʻo. ʻO ka hiki ke hoʻohui maikaʻi i nā mea optoelectronic GaN me nā mea uila Si i ka wā e hiki mai ana i ka ulu ʻana o ka epitaxy GaN ma ke silika.
Eia nō naʻe, ma muli o ka ʻokoʻa nui o ka lattice mau ma waena o Si substrate a me GaN material, heterogeneous epitaxy o GaN ma Si substrate he epitaxy mismatch nui maʻamau, a pono hoʻi ia e kū i nā pilikia:
✔ ʻO ka pilikia o ka ikehu o ka honua. Ke ulu ʻo GaN ma kahi pāpaʻi Si, e hoʻopili mua ʻia ka ʻili o ka substrate Si e hana i kahi papa nitride silicon amorphous i kūpono ʻole i ka nucleation a me ka ulu ʻana o GaN kiʻekiʻe. Eia kekahi, e hoʻopili mua ka ʻili Si iā Ga, kahi e hoʻopau ai i ka ʻili o ka substrate Si. Ma nā wela kiʻekiʻe, e laha ka decomposition o ka ʻili Si i loko o ka papa epitaxial GaN e hana i nā kiko silika ʻeleʻele.
✔ He nui ka lattice ma waena o GaN a me Si (~ 17%), kahi e alakaʻi ai i ka hoʻokumu ʻana i nā dislocations threading kiʻekiʻe a hoʻemi nui i ka maikaʻi o ka papa epitaxial;
✔ Hoʻohālikelike ʻia me Si, ʻoi aku ka nui o ka hoʻonui wela wela o GaN (ʻo ka nui o ka hoʻonui wela wela o GaN ma kahi o 5.6 × 10-6K-1, ʻo ka nui o ka hoʻonui wela o Si ma kahi o 2.6 × 10-6K-1), a hiki ke hana ʻia nā māwae i ka GaN papa epitaxial i ka wā o ka hoʻoluʻu ʻana o ka mahana epitaxial i ka mahana lumi;
✔ Hoʻopili ʻo Si me NH3 ma nā wela kiʻekiʻe e hana i ka polycrystalline SiNx. ʻAʻole hiki iā AlN ke hoʻokumu i kahi nucleus i koho ʻia ma polycrystalline SiNx, e alakaʻi ana i kahi orientation ʻino o ka papa GaN i ulu aʻe a me ka helu kiʻekiʻe o nā hemahema, e hopena i ka maikaʻi ʻole o ke aniani epitaxial layer GaN, a me ka paʻakikī hoʻi i ka hana ʻana i hoʻokahi-crystalline. GaN epitaxial layer [6].
I mea e hoʻoponopono ai i ka pilikia o ka lattice mismatch nui, ua hoʻāʻo nā mea noiʻi e hoʻolauna i nā mea e like me AlAs, GaAs, AlN, GaN, ZnO, a me SiC ma ke ʻano he papa pale ma nā substrates Si. I mea e pale aku ai i ka hoʻokumu ʻana o polycrystalline SiNx a hōʻemi i kona mau hopena maikaʻi ʻole i ka maikaʻi aniani o nā mea GaN / AlN / Si (111), pono e hoʻokomo ʻia ʻo TMal no kekahi manawa ma mua o ka ulu ʻana o ka epitaxial o ka papa pale AlN. no ka pale ʻana i ka NH3 mai ka hana ʻana me ka ʻili Si i hōʻike ʻia e hana i SiNx. Eia kekahi, hiki ke hoʻohana ʻia nā ʻenehana epitaxial e like me ka ʻenehana substrate patterned e hoʻomaikaʻi i ka maikaʻi o ka papa epitaxial. ʻO ka hoʻomohala ʻana o kēia mau ʻenehana e kōkua i ka pale ʻana i ka hoʻokumu ʻana o SiNx ma ka epitaxial interface, e hoʻoikaika i ka ulu ʻelua-dimensional o ka papa epitaxial GaN, a hoʻomaikaʻi i ka maikaʻi o ka ulu ʻana o ka papa epitaxial. Eia hou, ua hoʻokomo ʻia kahi papa pale AlN e uku ai i ke koʻikoʻi tensile i hoʻokumu ʻia e ka ʻokoʻa o nā coefficient hoʻonui wela e pale aku i nā māwae i ka papa epitaxial GaN ma ka substrate silicon. Hōʻike ka noiʻi a Krost he pilina maikaʻi ma waena o ka mānoanoa o ka papa pale AlN a me ka hōʻemi ʻana i ke koʻikoʻi. Ke piʻi ka mānoanoa o ka papa buffer i 12nm, hiki ke hoʻoulu ʻia kahi papa epitaxial mānoanoa ma mua o 6μm ma luna o kahi substrate silika ma o kahi hoʻolālā ulu kūpono me ka ʻole o ka haki ʻana o ka papa epitaxial.
Ma hope o nā hoʻoikaika lōʻihi a ka poʻe noiʻi, ua hoʻomaikaʻi maikaʻi ʻia ka maikaʻi o nā papa epitaxial GaN i ulu ʻia ma nā substrates silicon, a ua holomua nui nā mea like me nā transistors hopena kahua, Schottky barrier ultraviolet detectors, blue-green LEDs a me nā laser ultraviolet.
I ka hōʻuluʻulu manaʻo, ʻoiai ʻo nā substrates epitaxial GaN i hoʻohana mau ʻia he epitaxy heterogeneous, ke alo nei lākou a pau i nā pilikia maʻamau e like me ka lattice mismatch a me nā ʻokoʻa nui i nā coefficients hoʻonui wela i nā degere like ʻole. Hoʻopili ʻia nā substrates epitaxial GaN homogeneous e ka oʻo ʻana o ka ʻenehana, a ʻaʻole i hana nui ʻia nā substrates. He kiʻekiʻe ke kumukūʻai hana, liʻiliʻi ka nui o ka substrate, a ʻaʻole kūpono ke ʻano o ka substrate. ʻO ka hoʻomohala ʻana i nā substrates epitaxial GaN hou a me ka hoʻomaikaʻi ʻana i ka maikaʻi epitaxial kekahi o nā mea koʻikoʻi e kāohi ana i ka hoʻomohala hou ʻana o ka ʻoihana epitaxial GaN.
IV. Nā ala maʻamau no ka epitaxy GaN
MOCVD (ka hoʻomoe ʻana i ka mahu kemika)
Me he mea lā ʻo ka epitaxy homogeneous ma nā substrates GaN ke koho maikaʻi loa no ka epitaxy GaN. Eia naʻe, no ka mea, ʻo ka trimethylgallium a me ka amonia nā precursors o ka hoʻoheheʻe ʻana i ka mahu, a ʻo ke kinoea halihali he hydrogen, ʻo ka maʻamau o ka ulu ʻana o ka MOCVD ma kahi o 1000-1100 ℃, a ʻo ka nui o ka ulu ʻana o MOCVD e pili ana i kahi mau microns i kēlā me kēia hola. Hiki iā ia ke hana i nā pilina kiʻekiʻe ma ka pae atomika, kūpono loa ia no ka ulu ʻana i nā heterojunctions, quantum wells, superlattices a me nā hale ʻē aʻe. Hoʻohana pinepine ʻia kona ulu wikiwiki ʻana, kūlike maikaʻi, a kūpono no ka ulu ʻana o nā ʻāpana nui a me nā ʻāpana he nui i ka hana ʻoihana.
MBE (molecular beam epitaxy)
I loko o ka molecular beam epitaxy, hoʻohana ʻo Ga i kahi kumu kumu, a loaʻa mai ka nitrogen ikaika mai ka nitrogen ma o ka plasma RF. Ke hoʻohālikelike ʻia me ke ʻano MOCVD, ʻo ka ulu ʻana o ka MBE ma kahi o 350-400 ℃ haʻahaʻa. Hiki i ka ha'aha'a ha'aha'a o ka ulu 'ana ke pale aku i kekahi pollution i hiki ke kumu mai ka wela wela. Ke hana nei ka ʻōnaehana MBE ma lalo o ka ʻūhā kiʻekiʻe kiʻekiʻe, kahi e hiki ai iā ia ke hoʻohui i nā ʻano hana ʻike i loko. I ka manawa like, ʻaʻole hiki ke hoʻohālikelike ʻia kona ulu ulu a me ka mana hana me MOCVD, a ua hoʻohana ʻia i ka noiʻi ʻepekema [7].
Kiʻi 5 (a) Eiko-MBE schematic (b) MBE kumu hoʻohālike keʻena keʻena.
ʻO ke ala HVPE (hydride vapor phase epitaxy)
ʻO nā mea mua o ka hydride vapor phase epitaxy method he GaCl3 a me NH3. ʻO Detchprohm et al. ua hoʻohana i kēia ʻano hana e ulu i kahi papa epitaxial GaN he mau haneli microns mānoanoa ma ka ʻili o kahi substrate sapphire. I loko o kā lākou hoʻokolohua, ua ulu kahi papa o ZnO ma waena o ka substrate sapphire a me ka papa epitaxial ma ke ʻano he papa pale, a ua ʻili ʻia ka papa epitaxial mai ka ʻili o ka substrate. Ke hoʻohālikelike ʻia me MOCVD a me MBE, ʻo ka hiʻohiʻona nui o ke ʻano HVPE ʻo ia kona ulu ulu kiʻekiʻe, kahi kūpono no ka hana ʻana i nā papa mānoanoa a me nā mea nui. Eia nō naʻe, ke ʻoi aku ka mānoanoa o ka papa epitaxial ma mua o 20μm, hiki i ka papa epitaxial i hana ʻia e kēia ʻano hana i nā māwae.
Ua hoʻokomo ʻo Akira USUI i ka ʻenehana substrate ma muli o kēia ʻano. Ua ulu mua lākou i kahi ʻāpana epitaxial GaN mānoanoa 1-1.5μm mānoanoa ma kahi substrate sapphire me ka hoʻohana ʻana i ke ʻano MOCVD. Aia ka papa epitaxial i kahi papa pale GaN manoanoa 20nm i ulu ma lalo o nā kūlana wela haʻahaʻa a me kahi papa GaN i ulu ma lalo o nā kūlana wela kiʻekiʻe. A laila, ma 430 ℃, ua uhi ʻia kahi papa o SiO2 ma luna o ka ʻili o ka papa epitaxial, a ua hana ʻia nā kaha puka makani ma ke kiʻi SiO2 e ka photolithography. ʻO 7μm ka spacing a me ka laulā mask mai 1μm a 4μm. Ma hope o kēia hoʻomaikaʻi ʻana, ua loaʻa iā lākou kahi papa epitaxial GaN ma kahi substrate sapphire 2-inihi anawaena i māwae ʻole a maʻalahi e like me ke aniani ʻoiai ke piʻi ka mānoanoa i ʻumi a i ʻole haneli mau microns. Ua hōʻemi ʻia ka defect density mai 109-1010cm-2 o ke ʻano HVPE kuʻuna i kahi 6 × 107cm-2. Ua kuhikuhi pū lākou i loko o ka hoʻokolohua inā ʻoi aku ka nui o ka ulu ʻana ma mua o 75μm / h, e lilo ka ʻili o ka laʻana i mea ʻala[8].
Kiʻi 6 Kiʻi Kiʻi Substrate Schematic
V. Hōʻuluʻulu manaʻo a me Outlook
GaN mea hoomaka ae la e puka mai i loko o 2014 ka uliuli malamalama LED lanakila i ka Nobel makana ma Physics ia makahiki, a komo i ka lehulehu ka mahina o ka hookeai palapala noi ma ka consumer uila kahua. ʻO ka ʻoiaʻiʻo, ua puka mālie nā noi i nā mana amplifiers a me nā polokalamu RF i hoʻohana ʻia ma nā kahua kahua 5G i ʻike ʻole ʻia e ka hapa nui o ka poʻe. I kēia mau makahiki i hala iho nei, ua manaʻo ʻia ka holomua o nā mana mana automotive-grade GaN e wehe i nā wahi ulu hou no ka mākeke noi waiwai GaN.
ʻO ka noi nui o ka mākeke e hoʻolaha i ka hoʻomohala ʻana i nā ʻoihana pili a me nā ʻenehana pili GaN. Me ka oʻo ʻana a me ka hoʻomaikaʻi ʻana o ke kaulahao ʻoihana e pili ana i ka GaN, e hoʻomaikaʻi a lanakila paha nā pilikia e kū nei i ka ʻenehana epitaxial GaN i kēia manawa. I ka wā e hiki mai ana, e hoʻomohala nā kānaka i nā ʻenehana epitaxial hou a me nā koho substrate maikaʻi loa. I kēlā manawa, hiki i nā kānaka ke koho i ka ʻenehana noiʻi waho kūpono a me ka substrate no nā hiʻohiʻona noiʻi like ʻole e like me nā hiʻohiʻona o nā hiʻohiʻona noi, a hana i nā huahana hoʻokūkū hoʻokūkū.
Ka manawa hoʻouna: Iune-28-2024