| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a crystal of high performance by suppressing warpages occurring in a wafer (including a crystal layer grown with sapphire substrate) which prevents proper crystal growth, when a heterojunction layer comprising a GaN compound semiconductor layer is crystal grown on a sapphire substrate. SOLUTION: An active layer 3 of InGaN, while being sandwiched between an n-GaN clad layer 2 and a p-AlGaN clad layer 4 is grown to form a hetero structure. Here, large change in growth temperature required for it results in difference in thermal expansions between a sapphire substrate 1 and a clad layer 2 for causing warp of a wafer. In order to relax warping, a groove 1g is formed on a sapphire substrate surface, where a semiconductor crystal laminated before crystal growth. The groove 1g absorbs expansion/shrinkage caused by thermal expansion, for relaxing warping. The groove may be used in common with that used for dicing.</p> |
