PROBLEM TO BE SOLVED: To provide a base, where an AlGaN crystal layer having reduced dislocation density is grown, even while an LEPS method is being used.;SOLUTION: Irregularities, where the LEPS method can be carried out, are machined on the surface of a crystal substrate 1, and a GaN-based crystal layer 2 is grown from the recess or projection. At this point, AlGaN layers 21, 23, 25, and 27, where an Al composition is small and AlGaN layers 22, 24, 26, and 28 where the Al composition is large are alternately grown as a lamination structure, and at the same time, they are grown, until an upper surface becomes flat. As a result, growth is made preferentially by the LEPS method while being AlGaN, and an AlGaN crystal layer is achieved.;COPYRIGHT: (C)2003,JPO
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