Mfundo Zaukadaulo ndi Njira Zopangira Ma Epitaxial Wafers a LED

Kuchokera pamagwiritsidwe ntchito a ma LED, zikuwonekeratu kuti epitaxial wafer material ndiye chigawo chachikulu cha LED. M'malo mwake, magawo ofunikira a optoelectronic monga kutalika kwa mafunde, kuwala, ndi magetsi akutsogolo amatsimikiziridwa ndi epitaxial material. Ukadaulo wa Epitaxial wafer ndi zida ndizofunikira kwambiri popanga, ndi Metal-Organic Chemical Vapor Deposition (MOCVD) kukhala njira yayikulu yokulira zigawo zoonda za kristalo za III-V, II-VI, ndi ma alloys awo. Pansipa pali zina zamtsogolo zaukadaulo wa LED epitaxial wafer.

1. Kupititsa patsogolo Njira Yakukula Kwamagawo Awiri

Pakalipano, kupanga malonda kumagwiritsa ntchito njira ziwiri za kukula, koma chiwerengero cha magawo omwe amatha kunyamulidwa kamodzi ndi ochepa. Ngakhale makina opangira ma 6-wafer ndi okhwima, makina onyamula zowotcha 20 akupangidwabe. Kuchulukitsa kuchuluka kwa zowotcha nthawi zambiri kumabweretsa kusakwanira kofanana mu zigawo za epitaxial. Zochitika zamtsogolo zidzayang'ana mbali ziwiri:

• Kupanga matekinoloje omwe amalola kutsitsa magawo ambiri muchipinda chimodzi chochitira, kuwapangitsa kukhala oyenera kupanga zazikulu komanso kuchepetsa mtengo.
• Kupititsa patsogolo zida zamagetsi, zobwerezabwereza zawafa imodzi.

2. Hydride Vapor Phase Epitaxy (HVPE) Technology

Ukadaulo uwu umathandizira kukula mwachangu kwa makanema okhuthala omwe ali ndi kachulukidwe kakang'ono kakusuntha, komwe kumatha kukhala gawo la kukula kwa homoepitaxial pogwiritsa ntchito njira zina. Kuphatikiza apo, makanema a GaN olekanitsidwa ndi gawo lapansi amatha kukhala m'malo mwa tchipisi tambiri ta GaN single-crystal. Komabe, HVPE ili ndi zovuta zina, monga kuvutikira pakuwongolera makulidwe ake komanso mpweya wowononga womwe umalepheretsa kukonzanso kwazinthu za GaN.

Si-doped HVPE-GaN

(a) Mapangidwe a Si-doped HVPE-GaN reactor; (b) Chithunzi cha 800 μm- thick Si-doped HVPE-GaN;

(c) Kugawidwa kwa ndende zonyamula zaufulu pamodzi ndi Si-doped HVPE-GaN

3. Selective Epitaxial Growth kapena Lateral Epitaxial Growth Technology

Njirayi imatha kuchepetsa kuchulukitsitsa kwa dislocation ndikuwongolera mtundu wa kristalo wa zigawo za GaN epitaxial. Njirayi ikuphatikizapo:

• Kuyika gawo la GaN pagawo loyenera (safiro kapena SiC).
• Kuyika chigoba cha polycrystalline SiO₂ pamwamba.
• Kugwiritsa ntchito kujambula ndi etching kupanga mazenera a GaN ndi zotchinga za SiO₂.Pakukula kotsatira, GaN imayamba kukula molunjika m'mawindo ndiyeno motsatira mizere ya SiO₂.

Chophika cha XKH cha GaN-on-Sapphire

4. Pendeo-Epitaxy Technology

Njirayi imachepetsa kwambiri zolakwika za lattice zomwe zimayambitsidwa ndi lattice ndi kusagwirizana kwa kutentha pakati pa gawo lapansi ndi epitaxial wosanjikiza, kupititsa patsogolo khalidwe la kristalo la GaN. Njirazi zikuphatikiza:

• Kukula GaN epitaxial wosanjikiza pa gawo lapansi loyenera (6H-SiC kapena Si) pogwiritsa ntchito njira ziwiri.
• Kupanga kuyika kosankha kwa gawo la epitaxial mpaka pansi, ndikupanga mzati wosinthana (GaN/buffer/substrate) ndi ma ngalande.
• Kukula magawo owonjezera a GaN, omwe amafalikira mozungulira kuchokera m'mbali mwa zipilala zoyambirira za GaN, zoyimitsidwa pamwamba pa ngalandezo.Popeza palibe chigoba chomwe chimagwiritsidwa ntchito, izi zimapewa kulumikizana pakati pa GaN ndi zida za mask.

Chophika cha XKH cha GaN-on-Silicon

5. Kukula kwa Short-Wavelength UV LED Epitaxial Materials

Izi zimayala maziko olimba a ma LED oyera a phosphor opangidwa ndi UV. Ma phosphor ambiri ochita bwino kwambiri amatha kusangalatsidwa ndi kuwala kwa UV, kupereka kuwala kowala kwambiri kuposa dongosolo laposachedwa la YAG:Ce, potero kupititsa patsogolo magwiridwe antchito oyera a LED.

6. Multi-Quantum Well (MQW) Chip Technology

M'mapangidwe a MQW, zonyansa zosiyanasiyana zimayikidwa pakukula kwa gawo lotulutsa kuwala kuti apange zitsime zamitundu yosiyanasiyana. Kuphatikizanso kwa ma photon otuluka m'zitsimezi kumatulutsa kuwala koyera mwachindunji. Njirayi imapangitsa kuti pakhale kuwala kowala, imachepetsa mtengo, komanso imathandizira kuyika ndi kuyang'anira dera, ngakhale imakhala ndi zovuta zambiri zaukadaulo.

7. Kupanga "Photon Recycling" Technology

Mu Januwale 1999, Sumitomo yaku Japan idapanga chowunikira choyera chogwiritsa ntchito ZnSe. Ukadaulo umaphatikizapo kukulitsa filimu yopyapyala ya CdZnSe pagawo laling'ono la kristalo la ZnSe. Ikayikidwa magetsi, filimuyi imatulutsa kuwala kwa buluu, komwe kumayenderana ndi gawo laling'ono la ZnSe kuti lipange kuwala kowonjezera kwachikasu, kumapangitsa kuwala koyera. Mofananamo, Boston University's Photonics Research Center inayika AlInGaP semiconductor compound pa blue GaN-LED kuti apange kuwala koyera.

8. LED Epitaxial Wafer Process Flow

① Epitaxial Wafer Fabrication:
Gawo laling'ono → Kamangidwe kamangidwe → Kakulidwe kotchinga → Kukula kwamtundu wa N-GaN → Kukula kwa MQW kotulutsa kuwala → Kukula kwamtundu wa P wa GaN → Annealing → Kuyesa (photoluminescence, X-ray) → Epitaxial wafer

② Kupanga Chip:
Epitaxial wafer → Mapangidwe a chigoba ndi kupanga → Photolithography → etching ya ion → elekitirodi yamtundu wa N (kuyika, kuyika, kuyika) → ma elekitirodi amtundu wa P (kuyika, kuyika, kuyika) → Dicing → Kuwunika kwa chip ndi kuyika.

Chophika cha ZMSH cha GaN-on-SiC