| 摘要 |
PROBLEM TO BE SOLVED: To prevent the occurrence of a cracking by providing anisotropy in the thermal expansion coefficient of at least one of a semiconductor substrate and semiconductor epitaxial layer, and satisfying the specific relation between the surface expansion coefficient of each layer and the temperature difference from the crystal growth temperature to the ambient temperature. SOLUTION: An AlN epitaxial layer 12 and GaN epitaxial layer 13 are sequentially grown on a 6H-SiC off substrate 11 in which the main surface of a substrate is formed off at 12 deg. from (10 to 10) surface in <000> direction. The surface expansion coefficientβof the main surface of the substrate 11 and the surface expansion coefficientαof the layer 13 opposed to the main surface of the substrate 11 satisfy the relation of (α-β).ΔT<=1.4×10<-3> , where the temperature difference from the crystal growth temperature to the ambient temperature isΔT. Thus, the GaN compound semiconductor layer is epitaxially grown without generating cracking.
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