Technical Principles thiab Txheej Txheem ntawm LED Epitaxial Wafers

Los ntawm txoj haujlwm ua haujlwm ntawm LEDs, nws pom tseeb tias cov khoom siv epitaxial wafer yog cov tseem ceeb ntawm LED. Qhov tseeb, qhov tseem ceeb optoelectronic tsis xws li wavelength, brightness, thiab forward voltage feem ntau txiav txim siab los ntawm cov khoom siv epitaxial. Epitaxial wafer thev naus laus zis thiab khoom siv yog qhov tseem ceeb rau cov txheej txheem tsim khoom, nrog Hlau-Organic Chemical Vapor Deposition (MOCVD) yog thawj txoj hauv kev loj hlob nyias ib leeg-crystal txheej ntawm III-V, II-VI compounds, thiab lawv cov alloys. Hauv qab no yog qee qhov kev hloov pauv yav tom ntej hauv LED epitaxial wafer thev naus laus zis.

1. Kev txhim kho ob-kauj ruam kev loj hlob

Tam sim no, kev lag luam ntau lawm siv txoj kev loj hlob ob-kauj ruam, tab sis tus naj npawb ntawm cov substrates uas tuaj yeem thauj khoom ib zaug yog txwv. Thaum 6-wafer systems yog cov paub tab, cov tshuab tuav ib ncig ntawm 20 wafers tseem tab tom txhim kho. Kev nce tus naj npawb ntawm wafers feem ntau ua rau tsis txaus sib xws hauv cov txheej txheem epitaxial. Kev txhim kho yav tom ntej yuav tsom mus rau ob qho kev qhia:

• Tsim cov thev naus laus zis uas tso cai rau kev thauj khoom ntau lub substrates nyob rau hauv ib qho tshuaj tiv thaiv chamber, ua rau lawv tsim nyog rau kev tsim khoom loj thiab txo nqi.
• Kev nce qib siab automated, rov ua dua ib qho khoom siv wafer.

2. Hydride Vapor Phase Epitaxy (HVPE) Technology

Cov cuab yeej no ua rau kev loj hlob sai ntawm cov yeeb yaj kiab tuab nrog qhov tsis tshua muaj qhov sib txawv, uas tuaj yeem ua cov substrates rau homoepitaxial kev loj hlob siv lwm txoj hauv kev. Tsis tas li ntawd, GaN cov yeeb yaj kiab sib cais los ntawm cov substrate yuav dhau los ua lwm txoj hauv kev rau GaN ib leeg-crystal chips. Txawm li cas los xij, HVPE muaj qhov tsis zoo, xws li teeb meem hauv kev tswj cov tuab tuab thiab cov tshuaj tiv thaiv corrosive gases uas cuam tshuam kev txhim kho ntxiv hauv GaN cov khoom purity.

Si-doped HVPE-GaN

(a) Cov qauv ntawm Si-doped HVPE-GaN reactor; (b) Duab ntawm 800 μm- tuab Si-doped HVPE-GaN;

(c) Kev faib tawm ntawm cov neeg nqa khoom pub dawb nrog txoj kab uas hla ntawm Si-doped HVPE-GaN

3. Selective Epitaxial Growth lossis Lateral Epitaxial Loj hlob Technology

Cov txheej txheem no tuaj yeem txo qhov sib txawv ntawm qhov sib txawv thiab txhim kho cov khoom siv lead ua zoo ntawm GaN epitaxial txheej. Cov txheej txheem muaj xws li:

• Depositing ib txheej GaN rau ntawm ib tug haum substrate (sapphire los yog SiC).
• Tso lub polycrystalline SiO₂ daim npog qhov ncauj rau saum.
• Siv photolithography thiab etching los tsim GaN qhov rais thiab SiO₂ daim npog qhov ncauj strips.Thaum txoj kev loj hlob tom ntej, GaN thawj zaug loj hlob vertically nyob rau hauv lub qhov rais thiab tom qab ntawd tom qab ntawm SiO₂ strips.

XKH's GaN-on-Sapphire wafer

4. Pendeo-Epitaxy Technology

Txoj kev no ua rau txo qis qhov tsis xws ntawm lattice los ntawm lattice thiab thermal mismatch ntawm substrate thiab epitaxial txheej, ntxiv dag zog rau GaN siv lead ua zoo. Cov kauj ruam muaj xws li:

• Loj hlob ib txheej GaN epitaxial ntawm lub substrate tsim nyog (6H-SiC los yog Si) siv ob-kauj ruam txheej txheem.
• Kev xaiv etching ntawm epitaxial txheej mus rau lub substrate, tsim alternating ncej (GaN / tsis / substrate) thiab trench lug.
• Loj hlob ntxiv GaN khaubncaws sab nraud povtseg, uas txuas ntxiv tom qab ntawm lub sidewalls ntawm tus thawj GaN ncej, raug tshem tawm ntawm lub trench.Txij li thaum tsis siv lub npog ntsej muag, qhov no zam kev sib cuag ntawm GaN thiab cov ntaub ntawv npog ntsej muag.

XKH's GaN-on-Silicon wafer

5. Kev loj hlob ntawm Short-Wavelength UV LED Epitaxial Materials

Qhov no nteg lub hauv paus ruaj khov rau UV-zoo siab phosphor-raws li dawb LEDs. Ntau cov phosphors ua haujlwm siab tuaj yeem ua rau muaj kev zoo siab los ntawm UV teeb, muab kev ua haujlwm zoo dua luminous dua li YAG: Ce system tam sim no, yog li nce kev ua haujlwm dawb LED.

6. Multi-Quantum Well (MQW) Chip Technology

Hauv MQW cov qauv, cov impurities sib txawv yog doped thaum lub sij hawm loj hlob ntawm lub teeb-emitting txheej los tsim cov quantum qhov sib txawv. Lub recombination ntawm photons tawm los ntawm cov qhov dej no ua rau lub teeb dawb ncaj qha. Txoj kev no txhim kho luminous efficiency, txo cov nqi, thiab simplifies ntim thiab Circuit Court tswj, txawm hais tias nws muaj kev sib tw ntau dua.

7. Kev tsim kho ntawm "Photon Recycling" Technology

Thaum Lub Ib Hlis Ntuj xyoo 1999, Nyiv Sumitomo tau tsim ib lub LED dawb siv cov khoom siv ZnSe. Cov thev naus laus zis suav nrog kev loj hlob ntawm CdZnSe nyias zaj duab xis ntawm ZnSe ib leeg-crystal substrate. Thaum hluav taws xob, zaj duab xis emits xiav lub teeb, uas cuam tshuam nrog ZnSe substrate los tsim lub teeb daj ntxiv, ua rau lub teeb dawb. Ib yam li ntawd, Boston University's Photonics Research Center tau teeb tsa ib qho AlInGaP semiconductor compound ntawm xiav GaN-LED los tsim lub teeb dawb.

8. LED Epitaxial Wafer txheej txheem ntws

① Epitaxial Wafer Fabrication:
Substrate → Tus qauv tsim → Buffer txheej kev loj hlob → N-type GaN txheej kev loj hlob → MQW lub teeb-emitting txheej kev loj hlob → P-type GaN txheej kev loj hlob → Annealing → Kev ntsuam xyuas (photoluminescence, X-ray) → Epitaxial wafer

② Chip Fabrication:
Epitaxial wafer → Mask tsim thiab fabrication → Photolithography → Ion etching → N-type electrode (deposition, annealing, etching) → P-type electrode (deposition, annealing, etching) → Dicing → Chip inspection and grading.

ZMSH's GaN-on-SiC wafer