Mfundo Zaukadaulo ndi Njira za Ma Wafers a LED Epitaxial

Kuchokera ku mfundo yogwirira ntchito ya ma LED, n'zoonekeratu kuti zinthu za epitaxial wafer ndiye gawo lalikulu la LED. Ndipotu, magawo ofunikira a optoelectronic monga kutalika kwa nthawi, kuwala, ndi mphamvu ya kutsogolo zimatsimikiziridwa kwambiri ndi zinthu za epitaxial. Ukadaulo wa epitaxial wafer ndi zida ndizofunikira kwambiri pakupanga, ndipo Metal-Organic Chemical Vapor Deposition (MOCVD) ndiyo njira yayikulu yopangira zigawo zopyapyala za makristalo amodzi a III-V, II-VI, ndi ma alloys awo. Pansipa pali zina mwazomwe zikuchitika mtsogolo muukadaulo wa epitaxial wafer wa LED.

1. Kukonza Njira Yokulira ya Masitepe Awiri

Pakadali pano, kupanga ma wafer kumaphatikizapo njira ziwiri zokulira, koma chiwerengero cha ma substrates omwe angapatsidwe nthawi imodzi ndi chochepa. Ngakhale makina a ma wafer 6 ndi okhwima, makina ogwiritsa ntchito ma wafer pafupifupi 20 akadali kupangidwa. Kuchulukitsa chiwerengero cha ma wafer nthawi zambiri kumabweretsa kusakwanira kofanana kwa zigawo za epitaxial. Zochitika zamtsogolo zidzayang'ana mbali ziwiri:

• Kupanga ukadaulo womwe umalola kuyika zinthu zambiri mu chipinda chimodzi chochitira zinthu, zomwe zimapangitsa kuti zikhale zoyenera kwambiri popanga zinthu zambiri komanso kuchepetsa ndalama.
• Kupititsa patsogolo zida zodzipangira zokha komanso zobwerezabwereza za wafer imodzi.

2. Ukadaulo wa Hydride Npor Phase Epitaxy (HVPE)

Ukadaulo uwu umathandiza kukula mofulumira kwa mafilimu okhuthala okhala ndi kusungunuka kochepa, komwe kungagwiritsidwe ntchito ngati maziko a kukula kwa homoepitaxial pogwiritsa ntchito njira zina. Kuphatikiza apo, mafilimu a GaN olekanitsidwa ndi substrate akhoza kukhala njira zina m'malo mwa ma chips a GaN single-crystal. Komabe, HVPE ili ndi zovuta, monga kuvutika kuwongolera makulidwe molondola komanso mpweya wowononga womwe umalepheretsa kuyera kwa zinthu za GaN.

HVPE-GaN yopangidwa ndi Si-doped

(a) Kapangidwe ka reactor ya Si-doped HVPE-GaN; (b) Chithunzi cha 800 μm- makulidwe a Si-doped HVPE-GaN;

(c) Kufalikira kwa kuchuluka kwa mankhwala onyamula momasuka m'mimba mwake mwa Si-doped HVPE-GaN

3. Ukadaulo Wosankha Kukula kwa Epitaxial kapena Kukula kwa Epitaxial Pambali

Njira imeneyi ingachepetsenso kuchulukana kwa dislocation ndikukweza mtundu wa kristalo wa zigawo za GaN epitaxial. Njirayi imaphatikizapo:

• Kuyika gawo la GaN pa gawo loyenera (safiro kapena SiC).
• Kuyika chigoba cha polycrystalline SiO₂ pamwamba.
• Kugwiritsa ntchito photolithography ndi etching popanga mawindo a GaN ndi mikwingwirima ya mask ya SiO₂.Pakukula kotsatira, GaN imakula koyamba molunjika m'mawindo kenako mozungulira pamwamba pa mipiringidzo ya SiO₂.

Wafer wa XKH wa GaN-on-Sapphire

4. Pendeo-Epitaxy Technology

Njirayi imachepetsa kwambiri zolakwika za lattice zomwe zimachitika chifukwa cha lattice ndi kusagwirizana kwa kutentha pakati pa substrate ndi epitaxial layer, zomwe zimapangitsa kuti GaN crystal quality ikhale yabwino. Njirazi zikuphatikizapo:

• Kukula gawo la GaN epitaxial pa gawo loyenera (6H-SiC kapena Si) pogwiritsa ntchito njira ziwiri.
• Kuchita kudulidwa kosankhidwa kwa gawo la epitaxial mpaka pansi, ndikupanga chipilala chosinthana (GaN/buffer/substrate) ndi kapangidwe ka ngalande.
• Kukulitsa zigawo zina za GaN, zomwe zimatambasuka kuchokera m'mbali mwa zipilala zoyambirira za GaN, zomwe zimapachikidwa pamwamba pa ngalande.Popeza palibe chigoba chomwe chimagwiritsidwa ntchito, izi zimapewa kukhudzana pakati pa GaN ndi zinthu zophimba chigoba.

Wafer wa XKH wa GaN-on-Silicon

5. Kupanga Zipangizo za Epitaxial za UV za UV za Short-Wavelength

Izi zimayika maziko olimba a ma LED oyera okhala ndi phosphor opangidwa ndi UV. Ma phosphor ambiri ogwira ntchito bwino amatha kusangalatsidwa ndi kuwala kwa UV, zomwe zimapangitsa kuti kuwalako kukhale kowala kwambiri kuposa njira ya YAG:Ce yomwe ilipo pano, motero kupititsa patsogolo magwiridwe antchito a LED yoyera.

6. Ukadaulo wa Chip wa Multi-Quantum Well (MQW)

Mu kapangidwe ka MQW, zonyansa zosiyanasiyana zimayikidwa panthawi yomwe gawo lotulutsa kuwala likukula kuti lipange zitsime zosiyanasiyana za quantum. Kubwezeretsanso kwa ma photon omwe amatuluka m'zitsimezi kumapanga kuwala koyera mwachindunji. Njirayi imawongolera magwiridwe antchito a kuwala, imachepetsa ndalama, komanso imapangitsa kuti kulongedza ndi kuyendetsa bwino ma circuit zikhale zosavuta, ngakhale kuti imabweretsa zovuta zambiri zaukadaulo.

7. Kupititsa patsogolo Ukadaulo wa “Kubwezeretsanso Photon”

Mu Januwale 1999, Sumitomo ya ku Japan idapanga LED yoyera pogwiritsa ntchito ZnSe. Ukadaulowu umaphatikizapo kukulitsa filimu yopyapyala ya CdZnSe pa ZnSe single-crystal substrate. Ikayikidwa magetsi, filimuyo imatulutsa kuwala kwabuluu, komwe kumagwirizana ndi ZnSe substrate kuti ipange kuwala kwachikasu kowonjezera, zomwe zimapangitsa kuwala koyera. Mofananamo, Photonics Research Center ya ku Boston University idayika AlInGaP semiconductor compound pa GaN-LED yabuluu kuti ipange kuwala koyera.

8. Kuyenda kwa Njira Yopangira Ma Wafer a LED Epitaxial

① Kupanga kwa Epitaxial Wafer:
Substrate → Kapangidwe ka kapangidwe kake → Kukula kwa gawo la Buffer → Kukula kwa gawo la GaN la mtundu wa N → Kukula kwa gawo lotulutsa kuwala kwa MQW → Kukula kwa gawo la GaN la mtundu wa P → Kuyika kwa Annealing → Kuyesa (photoluminescence, X-ray) → Epitaxial wafer

② Kupanga Chip:
Epitaxial wafer → Kapangidwe ndi kapangidwe ka chigoba → Photolithography → Ion etching → N-type electrode (deposition, annealing, etching) → P-type electrode (deposition, annealing, etching) → Dicing → Chip inspection ndi grading.

Chophimba cha ZMSH cha GaN-on-SiC