Avalanche photodiode

Abstract

The purpose of this disclosure is to provide an avalanche photodiode that reduces dark current and has a high-speed response. The avalanche photodiode comprises: a first semiconductor layer having p-type conductivity; a barrier layer deposited on one side of the first semiconductor layer, having p-type conductivity; a light-absorbing layer deposited on the side of the barrier layer opposite to the first semiconductor layer, having p-type conductivity; a second semiconductor layer deposited on the side of the light-absorbing layer opposite to the barrier layer; a multiplication layer deposited on the side of the second semiconductor layer opposite to the light-absorbing layer; and a third semiconductor layer deposited on the side of the multiplication layer opposite to the barrier layer. On the opposite side of the second semiconductor layer, it has an n-type conductivity; and the first semiconductor layer, the barrier layer, the light-absorbing layer, the second semiconductor layer, and the multiplication layer form a first mesa; the third semiconductor layer forms a second mesa; the second mesa is located further inside than the first mesa when viewed from above, and protrudes more than the first mesa in the thickness direction; the doping concentration of the barrier layer is higher than or equal to the doping concentration of the light-absorbing layer; the doping concentration of the second semiconductor layer is lower than or equal to the doping concentration of the light-absorbing layer.

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