Improvement of sensitivity of graphene photodetector by creating bandgap structure**Project supported by the National Natural Science Foundation of China (Grant No. 51271210), the Chongqing Municipal Research Program of Basic Research and Frontier Technology, China (Grant No. cstc2015jcyjBX0039), and the Foundation for the Creative Research Groups of Higher Education of Chongqing Municipality, China (Grant No. CXTDX201601016).

Abstract

Graphene has aroused large interest in optoelectronic applications because of its broad band absorption and ultrahigh electron mobility. However, the low absorption of 2.3% seriously limits its photoresponsivity and restricts the relevant applications. In this paper, a method to enhance the sensitivity of graphene photodetector is demonstrated by introducing electron trapping centers and creating a bandgap structure in graphene. The carrier lifetime obviously increases, and more carriers are collected by the electrodes. Compared with intrinsic graphene detector, the defective graphene photodetector possesses high photocurrent and low-driving-voltage, which gives rise to great potential applications in photodetector area.