Acid etching for accurate determination of dislocation density in GaN |
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Authors: | Xueping Xu R P Vaudo J Flynn G R Brandes |
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Affiliation: | (1) ATMI, Inc., 06810 Danbury, CT |
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Abstract: | Hot phosphoric-acid etching and atomic force microscopy (AFM) were used to etch and characterize various GaN materials, including
freestanding GaN grown by hydride vapor-phase epitaxy (HVPE), metal-organic chemical-vapor deposition (MOCVD) GaN films on
sapphire and silicon carbide, and homoepitaxial GaN films on polished freestanding-GaN wafers. It was found that etching at
optimal conditions can accurately reveal the dislocations in GaN; however, the optimal etch conditions were different for
samples grown by different techniques. The as-grown HVPE samples were most easily etched, while the MOCVD homoepitaxial films
were most difficult to etch. Etch-pit density (EPD) ranging from 4×106 cm−2 to 5×109 cm−2 was measured in close agreement with the respective dislocation density determined from transmission electron microscopy
(TEM). |
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Keywords: | GaN acid etching defect decoration dislocation density |
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