High-performance broadband photodetector with in-situ-grown Bi2Se3 film on micropyramidal Si substrate

Abstract

Topological insulators have broad applications in the new generation of electronic devices and optoelectronic devices. Due to its narrow bandgap of 0.3 eV, Bi2Se3 film is a promising material for applications regarding visible light and infrared photodetection. However, the performance of photodetectors based on Bi2Se3 film is usually limited by the low absorption rate and the poor junction quality. In this work, we directly grew Bi2Se3 film onto the micropyramidal silicon by low-cost physical vapor deposition (PVD) method. Due to the light trapping of the micropyramidal substrate, and the high junction quality resulted from in-situ grown interface, the Bi2Se3/Si heterostructure has good photoresponse under broadband laser illumination of wavelengths from 635 to 2700 nm, which includes an excellent photo-to-dark ratio of 1.01 × 104, dark current of 0.11 nA, specific detectivity of 1.24 × 1011 Jones, and a fast response speed of microseconds. The etching process is found to be critical for the improvement of photoresponse. Our studies show a promising way to develop simple-technology, low-cost, high-efficiency heterojunction.