Izimiso Zobuchwepheshe Nezinqubo Zama-LED Epitaxial Wafers

Kusukela esimisweni sokusebenza sama-LED, kusobala ukuthi izinto ze-epitaxial wafer ziyingxenye eyinhloko ye-LED. Eqinisweni, amapharamitha abalulekile e-optoelectronic afana nobude be-wavelength, ukukhanya, kanye ne-forward voltage anqunywa kakhulu yizinto ze-epitaxial. Ubuchwepheshe be-epitaxial wafer kanye nemishini kubalulekile enkambisweni yokukhiqiza, kanti i-Metal-Organic Chemical Vapor Deposition (MOCVD) iyindlela eyinhloko yokukhulisa izendlalelo ezincane zekristalu elilodwa zama-III-V, II-VI compounds, kanye nama-alloys awo. Ngezansi kunezinye izitayela zesikhathi esizayo kubuchwepheshe be-epitaxial wafer be-LED.

1. Ukuthuthukiswa Kwenqubo Yokukhula Ezinyathelo Ezimbili

Njengamanje, ukukhiqizwa kwezentengiselwano kusebenzisa inqubo yokukhula enezinyathelo ezimbili, kodwa inani lezinto ezingafakwa ngesikhathi esisodwa lilinganiselwe. Ngenkathi izinhlelo ze-wafer ezi-6 sezivuthiwe, imishini ephatha cishe ama-wafer angu-20 isathuthukiswa. Ukwandisa inani lama-wafer kuvame ukuholela ekungalinganini okwanele kwezingqimba ze-epitaxial. Intuthuko yesikhathi esizayo izogxila ezindleleni ezimbili:

• Ukuthuthukisa ubuchwepheshe obuvumela ukulayisha ama-substrate amaningi ekamelweni elilodwa lokusabela, okwenza afaneleke kakhulu ekukhiqizweni okukhulu kanye nokunciphisa izindleko.
• Ukuthuthukisa imishini ye-single wafer esebenza ngokuzenzakalelayo kakhulu futhi ephindaphindwayo.

2. Ubuchwepheshe be-Hydride Vapor Phase Epitaxy (HVPE)

Lobu buchwepheshe buvumela ukukhula okusheshayo kwamafilimu aminyene anobuningi obuphansi bokuhlukaniswa, okungasebenza njengezinto ezisetshenziswa ekukhuleni kwe-homoepitaxial kusetshenziswa ezinye izindlela. Ngaphezu kwalokho, amafilimu e-GaN ahlukaniswe ne-substrate angaba ezinye izindlela esikhundleni sama-chips e-GaN single-crystal. Kodwa-ke, i-HVPE inezinkinga, njengobunzima ekulawuleni ukujiya okuqondile kanye namagesi okusabela okubolayo avimbela ukuthuthukiswa okuqhubekayo kokuhlanzeka kwezinto ze-GaN.

I-HVPE-GaN efakwe i-Si-doped

(a) Isakhiwo se-reactor ye-Si-doped HVPE-GaN; (b) Isithombe se-Si-doped HVPE-GaN enobukhulu obungu-800 μm;

(c) Ukusatshalaliswa kokuhlushwa kwe-carrier yamahhala kububanzi be-Si-doped HVPE-GaN

3. Ubuchwepheshe Bokukhula Kwe-Epitaxial Okukhethayo noma Ubuchwepheshe Bokukhula Kwe-Epitaxial Engakwesobunxele

Le ndlela inganciphisa kakhulu ubuningi be-dislocation futhi ithuthukise ikhwalithi yekristalu yezingqimba ze-epitaxial ze-GaN. Inqubo ihilela:

• Ukufaka ungqimba lwe-GaN ku-substrate efanelekile (isafire noma i-SiC).
• Ukufaka isendlalelo semaski se-polycrystalline SiO₂ phezulu.
• Ukusebenzisa i-photolithography kanye nokuqopha ukudala amafasitela e-GaN kanye nemicu yemaski ye-SiO₂.Ngesikhathi sokukhula okulandelayo, i-GaN iqala ikhule iqonde emafasiteleni bese ikhula eceleni phezu kwemichilo ye-SiO₂.

I-wafer ye-XKH ye-GaN-on-Sapphire

4. Ubuchwepheshe bePendeo-Epitaxy

Le ndlela inciphisa kakhulu ukukhubazeka kwe-lattice okubangelwa yi-lattice kanye nokungafani kokushisa phakathi kwe-substrate kanye ne-epitaxial layer, okuthuthukisa kakhulu ikhwalithi yekristalu ye-GaN. Izinyathelo zifaka:

• Ukukhulisa ungqimba lwe-epitaxial lwe-GaN ku-substrate efanelekile (6H-SiC noma i-Si) kusetshenziswa inqubo enezinyathelo ezimbili.
• Ukwenza ukuqopha okukhethiwe kwengqimba ye-epitaxial kuye phansi kwe-substrate, ukudala izinsika ezishintshanayo (i-GaN/buffer/substrate) kanye nezakhiwo zomsele.
• Ukukhulisa izendlalelo ezengeziwe ze-GaN, ezinwebeka eceleni kusukela ezindongeni eziseceleni zezinsika ze-GaN zokuqala, ezilengiswe phezu kwemisele.Njengoba kungekho mask esetshenziswayo, lokhu kugwema ukuthintana phakathi kwezinto ze-GaN nezinto zemaski.

I-wafer ye-XKH ye-GaN-on-Silicon

5. Ukuthuthukiswa Kwezinto Zokwenziwa Ze-LED Epitaxial Ze-UV Ezifushane Ezine-Wavelength

Lokhu kubeka isisekelo esiqinile sama-LED amhlophe asekelwe ku-phosphor ashukunyiswa yi-UV. Ama-phosphor amaningi asebenza kahle kakhulu angashukunyiswa ukukhanya kwe-UV, anikeze ukusebenza kahle okuphezulu kunohlelo lwamanje lwe-YAG:Ce, ngaleyo ndlela kuthuthukiswe ukusebenza kwe-LED emhlophe.

6. Ubuchwepheshe be-Multi-Quantum Well (MQW) Chip

Ezakhiweni ze-MQW, ukungcola okuhlukene kuyafakwa ngesikhathi sokukhula kwengqimba ekhipha ukukhanya ukuze kudalwe imithombo ye-quantum ehlukahlukene. Ukuhlanganiswa kabusha kwama-photon akhishwa kule mithombo kukhiqiza ukukhanya okumhlophe ngqo. Le ndlela ithuthukisa ukusebenza kahle okukhanyayo, inciphisa izindleko, futhi yenza kube lula ukupakisha nokulawula isekethe, yize iletha izinselele ezinkulu zobuchwepheshe.

7. Ukuthuthukiswa Kobuchwepheshe “Bokusebenzisa Kabusha I-Photon”

NgoJanuwari 1999, iSumitomo yaseJapan yakha i-LED emhlophe isebenzisa izinto ze-ZnSe. Lobu buchwepheshe buhilela ukukhulisa ifilimu encane ye-CdZnSe ku-substrate ye-ZnSe eyodwa-crystal. Uma igesiwe, ifilimu ikhipha ukukhanya okuluhlaza okwesibhakabhaka, okuthintana ne-substrate ye-ZnSe ukukhiqiza ukukhanya okuphuzi okuhambisanayo, okuholela ekukhanyeni okumhlophe. Ngokufanayo, i-Photonics Research Center yaseBoston University yabeka i-AlInGaP semiconductor compound ku-GaN-LED eluhlaza okwesibhakabhaka ukukhiqiza ukukhanya okumhlophe.

8. Ukugeleza Kwenqubo Ye-LED Epitaxial Wafer

① Ukwenziwa kwe-Epitaxial Wafer:
I-Substrate → Umklamo wesakhiwo → Ukukhula kwesendlalelo se-Buffer → Ukukhula kwesendlalelo se-GaN sohlobo lwe-N → Ukukhula kwesendlalelo esikhipha ukukhanya kwe-MQW → Ukukhula kwesendlalelo se-GaN sohlobo lwe-P → Ukufakwa kwe-Annealing → Ukuhlolwa (i-photoluminescence, i-X-ray) → I-Epitaxial wafer

② Ukwenziwa kwama-Chip:
I-wafer ye-Epitaxial → Ukwakhiwa kwemaski kanye nokwakhiwa kwayo → I-Photolithography → Ukugoba kwe-Ion → I-electrode yohlobo lwe-N (ukubeka, ukunamathisela, ukugoba) → I-electrode yohlobo lwe-P (ukubeka, ukunamathisela, ukugoba) → Ukugoba → Ukuhlolwa kwe-Chip kanye nokuhlela.

I-wafer ye-GaN-on-SiC ye-ZMSH