| 摘要 |
PURPOSE:To obtain an avalanche photodiode which can be operated on a low applied voltage by varying an impurity concentration distribution in accordance with the distance from a P-N junction plane. CONSTITUTION:A symmetrical impurity distribution is provided in a reach- through type avalanche photodiode. In a P-type layer and an N<+> type layer, if the boundary of a P-N junction is taken as an origin and the distance from the origin is denoted by (x), the impurity concentration distribution is expressed symmetrically by a formula ax<n> (n<0). At the P-N junction of such impurity distribution, the smaller the (n), the lower the voltage at which an avalanche effect is induced and the larger the effect. The condition of the impurity concentration distribution ax<n> (n<0) in the P-N junction may be satisfied at least in one of the P-type side or the N-type side.
|
