Superior Performances of Self-Driven Near-Infrared Photodetectors Based on the SnTe:Si/Si Heterostructure Boosted by Bulk Photovoltaic Effect.

Abstract

The upsurge of new materials that can be used for near-infrared (NIR) photodetectors operated without cooling is crucial. As a novel material with a small bandgap of ≈0.28eV, the topological crystalline insulator SnTe has attracted considerable attention. Herein, this work demonstrates self-driven NIR photodetectors based on SnTe/Si and SnTe:Si/Si heterostructures. The SnTe/Si heterostructure has a high detectivity D* of 3.3 × 1012 Jones. By Si doping, the SnTe:Si/Si heterostructure reduces the dark current density and increases the photocurrent by ≈1 order of magnitude simultaneously, which improves the detectivity D* by ≈2 orders of magnitude up to 1.59×1014 Jones. Further theoretical analysis indicates that the improved device performance may be ascribed to the bulk photovoltaic effect (BPVE), in which doped Si atoms break the inversion symmetry and thus enable the generation of additional photocurrents beyond the heterostructure. In addition, the external quantum efficiency (EQE) measured at room temperature at 850nm increases by a factor of 7.5 times, from 38.5% to 289%. A high responsivity of 1979mA W-1 without bias and fast rising time of 8 µs are also observed. The significantly improved photodetection achieved by the Si doping is of great interest and may provide a novel strategy for superior photodetectors.