High sensitivity and low noise photodetector based on topological crystalline insulator SnTe/Si heterostructure

Abstract

Topological insulators, as a class of materials with narrow bulk bandgap and gapless surface states with response wavelengths covering infrared to terahertz, have great potential for application in new generation photodetector, but the large dark current and small photocurrent limit their application, so the device performance is generally improved by the method of heterogeneous integration. SnTe, as a topological crystalline insulator with multiple surface states, has a narrower forbidden bandwidth, it is suitable for the fabrication of infrared photodetector. In this work, SnTe thin films were deposited on Si substrates by magnetron sputtering, and SnTe/n-Si heterostructure photodetectors were fabricated on this basis. The photodetector exhibited good photoresponses in the visible near-infrared (532–1400 nm), with the responsivity (R) and normalized detectivity (D*) reaching 1.12 A/W, 5.17 × 10¹¹ Jones. Thanks to the formation of the built-in electric field at the SnTe/Si interface, the photogenerated carriers can be rapidly separated and transported, and the switching ratio reaches 10³. In addition, the rise time and fall time of the device are 218 μs and 174 μs, respectively. The good performance and simple preparation method make the device have a wide application prospect in the new generation of photodetector.