GaN substrate formed under controlled growth condition over GaN layer having discretely formed pits

摘要

In a process for producing a substrate for use in a semiconductor element: a first GaN layer having a plurality of pits at its upper surface is formed; and then a second GaN layer is formed by growing a GaN crystal over the first GaN layer until the upper surface of the second GaN layer becomes flattened. Each of the above plurality of pits has an opening area of 0.005 to 100 mum<2 >and a depth of 0.1 to 10.0 mum.