| 摘要 |
PURPOSE:To realize the uniform and high multiplication factor of a light-receiving device by a method wherein the depletion layer in the vicinity of a junction is sufficiently widened by joining a P<+> type InP layer and an N<+> type InP layer together, thereby enabling to reduce a dark current. CONSTITUTION:The spreading of a depletion layer is suppressed as compared with the part located directly below the guard ring 9, where no layer 14 exists, by the depletion layer located in the vicinity of the junction between the P<+> type InP layer 21 and the third InP layer 16 located under said layer 21, which is sufficiently spread out due to the layer 16 having N<+> type, thereby enabling to weaken the field strength of the spread part, and also by the existence of the second N<+> type InP layer 14 at the part directly below the layer 21. As a result, the reverse withstand voltage of the layer 21 part is lowered than that of a guard ring 9 part. Accordingly, a low-noise APD having a low dard current and a sufficient multiplication factor can be manufactured easily. |
