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Thick crack free AlN on SiC template |
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Applications: semi-insulating substrate for ·
Power AlGaN/GaN-based High Electron Mobility
Transistors ( HEMT) ·
Power blue and UV LEDs, and Laser Diodes
Schematic cross section of a AlN/SiC template |
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Properties: ·
High
electrical resistivity and thermal conductivity ·
Close lattice
and thermal match with GaN and AlGaN layers ·
Low defect
density in device structures ·
Thickness of
AlN is sufficient to provide reliable insulation and low current leakage ·
Fraction of
price of semi-insulating SiC ·
Positively
tested at customers enabling dramatic cost reduction of final HEMT devices |
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SEM image of cleaved edge |
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Material Properties
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Parameter |
Value |
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AlN layer |
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Thickness, microns |
0.2-10 |
10-20 |
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Surface |
As grown |
As grown regular Polished As grown smooth* |
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Typical dislocation density, cm-2 |
(0.5-5)E9 |
(1-9)E8 |
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Typical FWHM of x-ray RC omega-scan (00.2), arcsec |
<450 |
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Surface roughness, nm |
<0.5 for
polished AlN (measured by AFM
5x5 microns scan) |
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Electrical resistivity,
Ohm cm |
>1E9 (300K) >1E7 (500K) |
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Substrate |
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Material |
4H-SiC or 6H-SiC |
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Size, inch |
2,3
and 4 |
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Electrical conductivity |
n-type |
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Surface orientation |
(0001) Si face |
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Growth technology |
Stress control
Hydride Vapor Phase Epitaxy |
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* Epi ready AlN surface is smooth
enough to grow high power HEMTs without any additional polishing.
Available in 2-inch size only. Research grade templates are supplied at reduced price subject of availability. Contact TDI for additional information, prices and availability of templates |
References:
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1. O. Kovalenkov et al., Thick AlN layers grown by HVPE, J. Cryst. Growth 281 (2005) 87-92. |
Optical pictures of AlN surface at x500 magnification
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As
grown regular |
As
grown smooth |
Polished |
X-ray characterization:
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X-ray w-scan rocking curve FWHM map for 2-inch AlN/SiC epi wafer with 20 mm thick crack free AlN layer grown on electrically conducting 6H-SiC substrate . Average = 379 arcsec |
Electrical resistivity of AlN layer:
Etch Pit Density (EPD) Characterization:
EPD rapidly reduces with AlN thickness increase