Fabrication and characterization of novel high-speed InGaAs/InP uni-traveling-carrier photodetector for high responsivity**Project supported partially by the National Natural Science Foundation of China (Grant Nos. 61274044 and 61077049), the National Basic Research Program of China (Grant No. 2010CB327600), the Program of Key International Science and Technology Cooperation Projects, China (Grant No. 2011RR000100), the 111 Project of China (Grant No. B07005), the

Abstract

A top-illuminated circular mesa uni-traveling-carrier photodetector (UTC-PD) is proposed in this paper. By employing Gaussian graded doping in InGaAs absorption layer and InP depleted layer, the responsivity and high speed response characteristics of the device are optimized simultaneously. The responsivity up to 1.071 A/W (the external quantum efficiency of 86%) is obtained at 1550 nm with a 40-μm diameter device under 10-V reverse bias condition. Meanwhile, the dark current of 7.874 nA and the 3-dB bandwidth of 11 GHz are obtained with the same device at a reverse bias voltage of 3 V.