METHOD OF PRODUCING GaN-BASED FILM AND COMPOSITE SUBSTRATE USED THEREFOR

摘要

PROBLEM TO BE SOLVED: To provide a method of producing a GaN-based film capable of efficiently obtaining a GaN film having a large main surface area, less warpage, and good crystallinity, and to provide a composite substrate used therefor.SOLUTION: A method of producing a GaN-based film includes the steps of: preparing a composite substrate 10 including a support substrate 11 dissoluble in an etching solution and a single crystal film 13 arranged on a side of a main surface 11m of the support substrate 11, wherein a coefficient of thermal expansion in the main surface 11m of the support substrate 11 is more than 0.8 time and less than 1.2 times compared with a coefficient of thermal expansion of GaN crystal; depositing a GaN-based film 20 on a main surface 13m of the single crystal film 13 arranged on the side of the main surface 11m of the support substrate 11; and removing the support substrate 11 by dissolving the support substrate 11 in the etching solution.