Cov Ntsiab Cai thiab Cov Txheej Txheem ntawm LED Epitaxial Wafers

Los ntawm txoj cai ua haujlwm ntawm LEDs, nws yog qhov tseeb tias cov khoom siv epitaxial wafer yog lub hauv paus tseem ceeb ntawm LED. Qhov tseeb, cov yam ntxwv tseem ceeb ntawm optoelectronic xws li wavelength, qhov ci ntsa iab, thiab qhov hluav taws xob pem hauv ntej feem ntau yog txiav txim siab los ntawm cov khoom siv epitaxial. Cov thev naus laus zis thiab cov khoom siv Epitaxial wafer yog qhov tseem ceeb rau cov txheej txheem tsim khoom, nrog rau Metal-Organic Chemical Vapor Deposition (MOCVD) yog txoj hauv kev tseem ceeb rau kev loj hlob cov txheej nyias nyias ntawm III-V, II-VI cov khoom sib xyaw, thiab lawv cov alloys. Hauv qab no yog qee qhov kev hloov pauv yav tom ntej hauv LED epitaxial wafer technology.

1. Kev Txhim Kho ntawm Cov Txheej Txheem Loj Hlob Ob Kauj Ruam

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

• Tsim cov thev naus laus zis uas tso cai rau kev thauj khoom ntau cov khoom siv hauv ib lub chamber tshuaj tiv thaiv, ua rau lawv tsim nyog dua rau kev tsim khoom loj thiab txo nqi.
• Kev txhim kho cov khoom siv tsis siv neeg, rov ua dua ib leeg-wafer.

2. Kev Siv Tshuab Hydride Vapor Phase Epitaxy (HVPE)

Cov thev naus laus zis no ua rau cov zaj duab xis tuab nrog qhov ceev qis, uas tuaj yeem ua cov substrates rau kev loj hlob homoepitaxial siv lwm txoj kev. Tsis tas li ntawd, cov zaj duab xis GaN sib cais los ntawm cov substrate yuav dhau los ua lwm txoj hauv kev rau cov chips GaN ib leeg. Txawm li cas los xij, HVPE muaj qhov tsis zoo, xws li qhov nyuaj hauv kev tswj qhov tuab thiab cov pa roj corrosive 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 khoom siv thauj khoom dawb raws li txoj kab uas hla ntawm Si-doped HVPE-GaN

3. Kev Loj Hlob Epitaxial Xaiv Los Yog Kev Loj Hlob Lateral Epitaxial Technology

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

• Tso ib txheej GaN rau ntawm ib lub substrate tsim nyog (sapphire lossis SiC).
• Tso ib txheej polycrystalline SiO₂ rau saum.
• Siv cov duab photolithography thiab etching los tsim cov qhov rai GaN thiab cov kab xev ntsej muag SiO₂.Thaum lub sijhawm loj hlob tom qab ntawd, GaN thawj zaug loj hlob ntsug hauv cov qhov rai thiab tom qab ntawd sab nraud hla cov kab SiO₂.

XKH lub GaN-on-Sapphire wafer

4. Kev Siv Tshuab Pendeo-Epitaxy

Txoj kev no txo ​​cov teeb meem lattice uas tshwm sim los ntawm lattice thiab thermal mismatch ntawm substrate thiab epitaxial txheej, ntxiv txhim kho GaN crystal zoo. Cov kauj ruam suav nrog:

• Kev loj hlob ntawm GaN epitaxial txheej rau ntawm ib lub substrate tsim nyog (6H-SiC lossis Si) siv cov txheej txheem ob kauj ruam.
• Ua qhov kev xaiv etching ntawm cov txheej epitaxial mus rau hauv lub substrate, tsim cov ncej hloov pauv (GaN / buffer / substrate) thiab cov qauv trench.
• Kev loj hlob ntxiv cov txheej GaN, uas txuas ntxiv mus rau sab nraud ntawm cov phab ntsa ntawm cov ncej GaN qub, dai rau saum cov qhov av.Vim tias tsis siv lub npog ntsej muag, qhov no zam kev sib cuag ntawm GaN thiab cov ntaub ntawv npog ntsej muag.

XKH lub GaN-on-Silicon wafer

5. Kev Tsim Kho Cov Khoom Siv UV LED Epitaxial Luv-Wavelength

Qhov no tso lub hauv paus ruaj khov rau cov LEDs dawb uas muaj UV-excited phosphor. Ntau lub phosphors ua haujlwm siab tuaj yeem raug txhawb los ntawm lub teeb UV, muab kev ua haujlwm ci ntsa iab dua li qhov system YAG: Ce tam sim no, yog li ua rau kev ua haujlwm dawb LED zoo dua.

6. Kev Siv Tshuab Chip Multi-Quantum Well (MQW)

Hauv cov qauv MQW, cov khoom tsis huv sib txawv raug doped thaum lub sijhawm loj hlob ntawm cov txheej txheem teeb pom kev zoo los tsim cov qhov dej quantum sib txawv. Kev sib xyaw ua ke ntawm cov photons tawm ntawm cov qhov dej no tsim cov teeb dawb ncaj qha. Txoj kev no txhim kho kev ua haujlwm zoo, txo cov nqi, thiab ua kom yooj yim rau kev ntim khoom thiab kev tswj hwm Circuit Court, txawm hais tias nws nthuav tawm cov teeb meem kev siv tshuab ntau dua.

7. Kev Tsim Kho Tshuab "Photon Recycling"

Thaum Lub Ib Hlis Ntuj xyoo 1999, Sumitomo ntawm Nyiv tau tsim ib lub LED dawb siv cov khoom siv ZnSe. Cov thev naus laus zis no suav nrog kev cog ib daim zaj duab xis nyias CdZnSe rau ntawm ib lub substrate ZnSe ib leeg-crystal. Thaum hluav taws xob, daim zaj duab xis tso tawm lub teeb xiav, uas cuam tshuam nrog lub substrate ZnSe los tsim lub teeb daj sib txuas, ua rau lub teeb dawb. Ib yam li ntawd, Boston University's Photonics Research Center tau teeb tsa ib qho AlInGaP semiconductor compound rau ntawm ib lub GaN-LED xiav los tsim lub teeb dawb.

8. LED Epitaxial Wafer Txheej Txheem Flow

① Epitaxial Wafer Tsim:
Cov khoom siv → Tsim qauv → Kev loj hlob ntawm cov txheej txheem buffer → N-hom GaN txheej kev loj hlob → MQW lub teeb-emitting txheej kev loj hlob → P-hom GaN txheej kev loj hlob → Annealing → Kev sim (photoluminescence, X-ray) → Epitaxial wafer

② Kev Tsim Khoom Siv Chip:
Epitaxial wafer → Tsim thiab tsim lub ntsej muag → Photolithography → Ion etching → N-hom electrode (deposition, annealing, etching) → P-hom electrode (deposition, annealing, etching) → Dicing → Kev tshuaj xyuas Chip thiab qib.

ZMSH lub GaN-on-SiC wafer