| 摘要 |
PURPOSE:To prevent the penetration of impurities into an active layer by a method wherein the impurity contained at the highest concentration in the fourth semiconductor layer is the IV group element, and the impurity contained at the highest concentration in the semiconductor layer opposite to the second semiconductor layer with respect to the fourth semiconductor layer the II group element. CONSTITUTION:To suppress the diffusion of the II group element which is a p-type impurity source of high diffusion coefficient, a region doped with the IV group element which is an n-type impurity source is formed between an active layer 13 and a p-type region 17 to serve as an impurity diffusion suppressing layer 14. At this time, the highest concentration of the IV group element in the diffusion suppressing layer 14 is made higher than that of the II group element in the p-type region 17. That is, it is utilized that when p-type, n-type, and hetero-type impurities are present at the same time, interaction between the impurities reduces diffusion of impurities to make an impurity of high diffusion coefficient have a diffusion profile as sharp as an impurity of small diffusion coefficient. This can suppress the diffusion of the p-type impurity into the active layer 13. |
