| 摘要 |
PURPOSE:To obtain the light-receiving element having the withstand voltage design with leeway and also having no reflected light coming back to the source of light by a method wherein the light-receiving surface of an avalanche photodiode chip is attached to the stem by providing the desired angle on the incident light. CONSTITUTION:The chip attaching surface of the stem is inclined at the angle theta against the incident light hnu, and the chip is fixed on the inclined surface. The light hnu which is made incident on the light-receiving surface 10 at the angle theta proceeds diagonally in an ApD element and reaches in InGaAs. At this time, the thickness (d) down to the layer 3 is effectively increased to d/costheta. Accordingly, the distance passing through a depletion layer is increased too, and a pair of electron and hole generated by the light absorption at the upper part of the layer 3 can be obtained by having a sufficient field accelerating effect on a shallow depletion layer 41. Through these procedures, the increase in withstand voltage can be prevented by extending the depletion layer deeply, and the thickness and the density of an epitaxial layer is designed with leeway. Also, the light reflected by the light-receiving surface does not return to the light source, and the unstable state of optical oscillation mode of the light source can be prevented. |
