Influence of two-tier structuring on the performance of black silicon-based MSM photodetectors

Abstract

Black silicon, fabricated by alkaline anisotropic etching along with metal-assisted etching, consists of regular distributed micro-scale pyramids and irregular distributed nano-scale pores, in which the pore size plays an important role in the performance of the black silicon-based metal–semiconductor–metal photodetectors (BS MSM PDs). It is found that the dark current characteristic of BS MSM PD is different from that of traditional silicon MSM PD, and the former has negative differential resistance in part of its operating range because of the quantum tunneling effect exists in black silicon. Moreover, it is interesting to note that BS MSM PD with longer metal-assisted etching time (larger nanopore size) has higher responsivity at high bias voltage but lower responsivity at low bias voltage.