Pre-treatment of low temperature GaN buffer layer deposited on AlN/Si substrate by hydride vapor phase epitaxy

We investigated the effects of pre-treatments of a low temperature GaN (LT- GaN) buffer layer on its properties, and of a thick GaN film to improve its qualities. Pre-treatment was performed by annealing the LT-GaN buffer laye r under different conditions including different ambient gases (NH3 and N-2 ) and temperatures. We found that the pre-treatments of LT-GaN strongly aff ected surface morphology, crystallinity and optical property of GaN. Crysta llinity and optical property of the pre-treated LT-GaN were improved as com pared with as-deposited LT-GaN buffer layer. Thick GaN layers with high qua lity were also obtained by pre-treatment of LT-GaN buffer layer. Surface ro ughness, morphology and chemistry of the pre-treated LT-GaN buffer layer an d thick GaN film on AlN/Si substrate were examined by atomic force microsco py (AFM), scanning electron microscopy (SEM) and X-ray photoemission spectr oscopy (XPS) respectively. Optical characteristics and crystallinity of LT- GaN were measured by low temperature photoluminescence (PL), and X-ray diff ractometry (XRD), respectively. (C) 2000 Elsevier Science B.V. All rights r eserved.