| 摘要 |
PURPOSE:To prevent deterioration in electric characteristics of a device even at a high temperature during the current conduction for a long time, by the constitution, wherein different conducting type impurities are diffused in a region forming a crystal interface, and the position of a P-N junction is moved from the interface to the inside or to the outside. CONSTITUTION:The carrier concentration of P-type impurities in a P-InP layer 4 is denoted as Np, and the carrier concentration of N-type impurities in an N-InP layer 1, which is a substrate is denoted as Nn. In this case the relationship Np>Nn is established. For example, Zn, whose diffusion is easy, is selected as the P type impurities. An InGaAsP active layer is P-type. Then, the position of the P-N junction, which is exposed to the initial atmosphere, A, B, and C, and D, E, and F is moved to the position A', B', and C', and D', E', and F' in the N-InP layer 1. In this constitution, the exposed P-N junction interface, which becomes the cause of deterioration at a high temperature, is eliminated. As a result, a current can be concentrated in the active region 2a. |
