Ma semiconductor a Wide bandgap (WBG) omwe amaimiridwa ndi silicon carbide (SiC) ndi gallium nitride (GaN) alandiridwa kwambiri. Anthu ali ndi ziyembekezo zazikulu pakugwiritsa ntchito silicon carbide m'magalimoto amagetsi ndi ma gridi amagetsi, komanso kuthekera kwa kugwiritsa ntchito gallium nitride pakuchaja mwachangu. M'zaka zaposachedwa, kafukufuku pa Ga2O3, AlN ndi zida za diamondi wapita patsogolo kwambiri, zomwe zapangitsa kuti zida za semiconductor za ultra-wide bandgap zikhale zowunikira kwambiri. Pakati pawo, gallium oxide (Ga2O3) ndi chida cha semiconductor cha ultra-wide bandgap chomwe chili ndi band gap ya 4.8 eV, mphamvu yamunda yowunikira ya pafupifupi 8 MV cm-1, liwiro la saturation la pafupifupi 2E7cm s-1, komanso Baliga quality factor yapamwamba ya 3000, yomwe imalandira chidwi chachikulu m'munda wamagetsi amphamvu kwambiri komanso zamagetsi amphamvu kwambiri.
1. Makhalidwe a zinthu za Gallium oxide
Ga2O3 ili ndi mpata waukulu wa band gap (4.8 eV), ikuyembekezeka kukwaniritsa mphamvu zopirira mphamvu zambiri komanso mphamvu zambiri, ndipo ikhoza kukhala ndi kuthekera kosinthasintha mphamvu zamagetsi pakakhala kukana kochepa, zomwe zimapangitsa kuti ikhale maziko a kafukufuku waposachedwa. Kuphatikiza apo, Ga2O3 sikuti ili ndi zinthu zabwino zokha, komanso imapereka ukadaulo wosiyanasiyana wosinthika mosavuta wa n-type doping, komanso ukadaulo wotsika mtengo wa substrate ndi epitaxy. Pakadali pano, magawo asanu osiyana a kristalo apezeka mu Ga2O3, kuphatikiza corundum (α), monoclinic (β), defective spinel (γ), cubic (δ) ndi orthorhombic (ɛ). Kukhazikika kwa thermodynamic, motsatira, ndi γ, δ, α, ɛ, ndi β. Ndikofunikira kudziwa kuti monoclinic β-Ga2O3 ndiyo yokhazikika kwambiri, makamaka kutentha kwambiri, pomwe magawo ena ndi okhazikika kuposa kutentha kwa chipinda ndipo nthawi zambiri amasanduka gawo la β pansi pa kutentha kwina. Chifukwa chake, chitukuko cha zipangizo zopangidwa ndi β-Ga2O3 chakhala cholinga chachikulu pa nkhani ya zamagetsi m'zaka zaposachedwa.
Gome 1 Kuyerekeza kwa magawo ena a zinthu za semiconductor
Kapangidwe ka kristalo ka monoclinicβ-Ga2O3 kakuwonetsedwa mu Gome 1. Ma parameter ake a lattice akuphatikizapo a = 12.21 Å, b = 3.04 Å, c = 5.8 Å, ndi β = 103.8°. Selo ya unit ili ndi ma atomu a Ga(I) okhala ndi mgwirizano wopindika wa tetrahedral ndi ma atomu a Ga(II) okhala ndi mgwirizano wa octahedral. Pali makonzedwe atatu osiyana a ma atomu a okosijeni mu gulu la "twisted cubic", kuphatikiza ma atomu awiri a O(I) ndi O(II) olumikizidwa ndi triangularly ndi atomu imodzi ya O(III) yolumikizidwa ndi tetrahedral. Kuphatikiza kwa mitundu iwiriyi ya mgwirizano wa atomu kumabweretsa anisotropy ya β-Ga2O3 yokhala ndi mawonekedwe apadera mu fizikisi, dzimbiri la mankhwala, optics ndi zamagetsi.
Chithunzi 1 Chithunzi cha kapangidwe kake ka kristalo ya monoclinic β-Ga2O3
Kuchokera pamalingaliro a chiphunzitso cha mphamvu, mtengo wocheperako wa gulu loyendetsa la β-Ga2O3 umachokera ku mkhalidwe wa mphamvu wofanana ndi 4s0 hybrid orbit ya atomu ya Ga. Kusiyana kwa mphamvu pakati pa mtengo wocheperako wa gulu loyendetsa ndi mulingo wa mphamvu ya vacuum (mphamvu ya electron affinity) kumayesedwa. ndi 4 eV. Kulemera kwa ma electron kogwira ntchito kwa β-Ga2O3 kumayesedwa ngati 0.28–0.33 me ndi mphamvu yake yabwino yamagetsi. Komabe, kuchuluka kwa valence band kumawonetsa shallow Ek curve yokhala ndi kupindika kochepa kwambiri komanso ma orbitals a O2p omwe ali pamalo amodzi, zomwe zikusonyeza kuti mabowo ali pamalo amodzi kwambiri. Makhalidwe amenewa ndi ovuta kwambiri kuti tikwaniritse p-type doping mu β-Ga2O3. Ngakhale P-type doping ingapezeke, dzenje μ limatsalira pamlingo wotsika kwambiri. 2. Kukula kwa kristalo imodzi ya gallium oxide yochuluka Mpaka pano, njira yokulira ya β-Ga2O3 yochuluka ya kristalo imodzi makamaka ndi njira yokokera kristalo, monga Czochralski (CZ), njira yodyetsera filimu yopyapyala (Edge -Defined film-fed, EFG), Bridgman (Bridgman, HB kapena VB) ndi ukadaulo wa floating zone (floating zone, FZ). Pakati pa njira zonse, njira zodyetsera Czochralski ndi edge-defined thin-film feeding zikuyembekezeka kukhala njira zabwino kwambiri zopangira ma wafers a β-Ga 2O3 mtsogolo, chifukwa nthawi imodzi amatha kupeza kuchuluka kwakukulu komanso kuchuluka kochepa kwa zolakwika. Mpaka pano, Novel Crystal Technology yaku Japan yapeza njira yogulitsira β-Ga2O3 yosungunuka.
1.1 Njira ya Czochralski
Mfundo ya njira ya Czochralski ndi yakuti gawo la mbewu liziphimbidwa kaye, kenako kristalo imodzi imachotsedwa pang'onopang'ono kuchokera ku kusungunuka. Njira ya Czochralski ndiyofunika kwambiri pa β-Ga2O3 chifukwa cha mtengo wake wotsika, mphamvu zake zazikulu, komanso kukula kwapamwamba kwa substrate ya kristalo. Komabe, chifukwa cha kutentha kwambiri panthawi ya kukula kwa kutentha kwa Ga2O3, kutuluka kwa makristalo amodzi, zinthu zosungunuka, ndi kuwonongeka kwa Ir crucible zidzachitika. Izi ndi zotsatira za kuvutika kupeza doping yochepa ya n-type mu Ga2O3. Kuyika mpweya wokwanira mumlengalenga wokulira ndi njira imodzi yothetsera vutoli. Kudzera mu kukonza bwino, β-Ga2O3 yapamwamba kwambiri ya mainchesi 2 yokhala ndi kuchuluka kwa ma electron kwaulere kwa 10^16~10^19 cm-3 ndi kuchuluka kwa ma electron kwakukulu kwa 160 cm2/Vs kwakulitsidwa bwino ndi njira ya Czochralski.
Chithunzi 2 Krustalo imodzi ya β-Ga2O3 yomwe imakula pogwiritsa ntchito njira ya Czochralski
1.2 Njira yodyetsera filimu yofotokozedwa m'mphepete
Njira yodyetsera filimu yopyapyala yopangidwa m'mphepete imaonedwa kuti ndiyo njira yotsogola yopangira zinthu zazikulu za Ga2O3 za kristalo imodzi. Mfundo ya njira iyi ndikuyika kusungunuka mu nkhungu yokhala ndi kagawo ka capillary, ndipo kusungunuka kumakwera kupita ku nkhungu kudzera mu capillary action. Pamwamba, filimu yopyapyala imapangidwa ndikufalikira mbali zonse pamene ikukakamizidwa kuti ipangitse kristalo kukhala yopyapyala. Kuphatikiza apo, m'mphepete mwa pamwamba pa nkhungu mutha kulamulidwa kuti mupange makristalo mu ma flakes, machubu, kapena geometry iliyonse yomwe mukufuna. Njira yodyetsera filimu yopyapyala yopangidwa m'mphepete mwa Ga2O3 imapereka kukula mwachangu komanso mainchesi akulu. Chithunzi 3 chikuwonetsa chithunzi cha kristalo imodzi ya β-Ga2O3. Kuphatikiza apo, pankhani ya kukula, ma substrates a 2-inch ndi 4-inch β-Ga2O3 okhala ndi mawonekedwe abwino komanso ofanana agulitsidwa, pomwe substrate ya 6-inch ikuwonetsedwa mu kafukufuku wa malonda amtsogolo. Posachedwapa, zipangizo zazikulu zozungulira za kristalo imodzi zapezekanso ndi (−201). Kuphatikiza apo, njira yodyetsera filimu ya β-Ga2O3 m'mphepete imalimbikitsanso kugwiritsa ntchito mankhwala osokoneza bongo a zinthu zachitsulo zosinthira, zomwe zimapangitsa kuti kafukufuku ndi kukonzekera kwa Ga2O3 kutheke.
Chithunzi 3 β-Ga2O3 kristalo imodzi yomwe imakulitsidwa pogwiritsa ntchito njira yodyetsera filimu yofotokozedwa m'mphepete
1.3 Njira ya Bridgeman
Mu njira ya Bridgeman, makhiristo amapangidwa mu choyimitsira chomwe chimasunthidwa pang'onopang'ono kudzera mu kutentha. Njirayi ikhoza kuchitika molunjika kapena molunjika, nthawi zambiri pogwiritsa ntchito choyimitsira chozungulira. Ndikofunikira kudziwa kuti njira iyi ingagwiritse ntchito mbewu za kristalo kapena ayi. Ogwiritsa ntchito achikhalidwe a Bridgman satha kuwona mwachindunji njira zosungunulira ndi kukula kwa makhiristo ndipo ayenera kuwongolera kutentha molondola kwambiri. Njira ya Bridgman yoyimitsidwa imagwiritsidwa ntchito makamaka pakukula kwa β-Ga2O3 ndipo imadziwika kuti imatha kukula mumlengalenga. Pakukula kwa njira ya Bridgman yoyimitsidwa, kutayika konse kwa kusungunuka ndi choyimitsidwa kumakhala pansi pa 1%, zomwe zimathandiza kukula kwa makhiristo akuluakulu a β-Ga2O3 osatayika kwambiri.
Chithunzi 4 Krustalo imodzi ya β-Ga2O3 yomwe imakula pogwiritsa ntchito njira ya Bridgeman
1.4 Njira yoyandama
Njira yoyandama m'dera imathetsa vuto la kuipitsidwa kwa makristalo ndi zinthu zoyambira ndipo imachepetsa ndalama zambiri zomwe zimagwirizanitsidwa ndi ma infrared crucibles omwe sagwira kutentha kwambiri. Panthawi yokulira, kusungunuka kumatha kutenthedwa ndi nyali m'malo mwa gwero la RF, motero kumachepetsa zofunikira pazida zokulira. Ngakhale mawonekedwe ndi mtundu wa makristalo wa β-Ga2O3 womwe umalimidwa ndi njira yoyandama m'dera sizili bwino, njira iyi imatsegula njira yabwino yokulira makristalo a β-Ga2O3 okhala ndi chiyero chapamwamba kukhala makristalo amodzi omwe sawononga ndalama zambiri.
Chithunzi 5 β-Ga2O3 kristalo imodzi yomwe imakula pogwiritsa ntchito njira yoyandama.
Nthawi yotumizira: Meyi-30-2024