Abstract
Abstract An avalanche photodiode with internal gain made it have higher sensitivity in communication receiver. Therefore, It is suitable as photodetectors in long distance fiber communication or high sensitivity system. An avalanche photodiode with pn junction using planar diffusion process operated near the breakdown voltage. Because of the junction curvature effect, this will make the edge breakdown easily. This is a serious problem in photodetectors In order to reduce the edge breakdown effect and tailor the distribution of the electric field intensity, we added a charge layer and then etched by dry etching technology to form a mesa structure and re-grown a multiplication layer by MOCVD. We successfully fabricated five structures without guard ring structures. In conclusion, the dark current is about 4.28nA and the gain is around 10 at 0.95V breakdown voltage. The 3dB bandwidth is about 4.9GHz when the gain is 5.