| 摘要 |
On an upper surface of a silicon (Si) substrate, an Al0.2Ga0.8N layer having a film thickness of 0.2 mum to 0.3 mum and a GaN layer having a film thickness of 0.5 mum are formed successively. The resulting substrate is set in a halide VPE apparatus so that the resulting substrate can be independently etched with HCl gas from a rear surface of the resulting substrate. While a GaN layer is epitaxially grown on the GaN layer at 900° C. by a halide vapor-phase epitaxy method, the silicon (Si) substrate, the Al0.2Ga0.8N layer and the GaN layer are removed from the rear surface by gas etching. In this manner, the GaN layer having a film thickness of about 50 mum is obtained. While a GaN layer is epitaxially grown on the GaN layer at 1050° C. by a halide vapor-phase epitaxy method, the GaN layer is removed from the rear surface by gas etching. Finally, a substrate made of the GaN layer with a film thickness of 200 mum and free from any warp and any crack is obtained.
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