Effect of buffer layer preparation on GaN epilayers grown by gas-source molecular-beam epitaxy

1077-3118

AIP Digital Archive

Physics

Using gas-source molecular-beam epitaxy, and ammonia as a source of nitrogen, we have investigated the effect of buffer layer preparation on the electrical and optical properties of GaN epilayers. It is found that the buffer layer thickness and buffer anneal time have a dramatic effect on the Hall mobility and the background carrier density in the layers. With an optimized buffer layer, we have achieved mobility of ∼190 cm2/V s and have correlated this with a defect density as low as 2.1×109 cm−2 in the best layers. The variation of the intensity of defect related lines in photoluminescence spectra has been used to confirm the decrease of the defect density with increasing mobility in these layers. © 2001 American Institute of Physics.

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