GaN on ZrB2 substrates using LT-AlGaN as a nucleation layer
Abstract
We have studied the effect of the AlGaN nucleation layer on the crystalline quality of GaN epilayers. In order to find the optimum growth conditions, the deposition temperature of the AlGaN layer was varied from 600oC to 1100oC. GaN epilayers exhibit mirror-like surfaces when the AlGaN nucleation layer is deposited in the temperature range of 725-925oC. When the nucleation growth temperature is low (600oC), the GaN epilayers exhibit island structure. On the other hand, at a higher nucleation temperature of 1100oC, the GaN film has a rough morphology and many hexagonal column structures are observed on the surface. TEM studies have been carried out to investigate the microstructure of the samples. We show that samples with a smooth surface have a highly defective AlGaN nucleation layer, but most of the dislocations are annihilated in the early stage of GaN growth. However, in samples with very low or very high nucleation temperatures, the microstructure of the epilayers degrades.
- Publication:
-
APS Four Corners Section Meeting Abstracts
- Pub Date:
- October 2003
- Bibcode:
- 2003APS..4CF.S3005M