Reuse of ScAlMgO4 substrates utilized for halide vapor phase epitaxy of GaN

ScAlMgO 4 (SCAM) substrates with a small lattice-mismatch to GaN and c -plane cleavability are promising for fabricating high-quality free-standing GaN wafers. To reduce the cost in the fabrication of free-standing GaN wafers, the reuse of a SCAM substrate is demonstrated. By cleaving a SCAM substrate which has been already utilized for the growth of a thick GaN film by halide vapor phase epitaxy, the atomically flat surface can be obtained. The threading dislocation density of a 320 μ m thick GaN film grown on this cleaved SCAM substrate is 2.4 × 10 7  cm −2 , which is almost the same as that on a new SCAM substrate. This result indicates that a SCAM substrate can be reused for GaN growth.