| 摘要 |
In a optoelectronic integrated circuit, a pin-type light receiving device and an electronic circuit device are electrically connected to each other and monolithically integrated on a semiconductor substrate. In the pin-type light receiving device, an n-type semiconductor layer, an i-type semiconductor layer, and a p-type semiconductor layer are sequentially formed on the semiconductor substrate and sequentially formed into mesa shapes. The first mesa is constituted by the p-type semiconductor layer, and the second mesa is constituted by the i-type semiconductor layer. The boundary surface between the first and second mesas is formed to match the junction surface between the p-type semiconductor layer and the i-type semiconductor layer. The diameter of the first mesa is formed smaller than that of the second mesa. With this structure, a depletion layer extending from the p-type semiconductor layer upon application of a reverse bias voltage stays within the i-type semiconductor layer and does not reach the surfaces of the first and second mesas to be exposed. For this reason, a dark current flowing in accordance with the interface state between the side surface of the mesa and an insulating layer for protecting the surface of the mesa is reduced. Therefore, a noise signal input in the electronic circuit device is reduced to improve the receiving sensitivity.
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