Self-power position-sensitive detector with fast optical relaxation time and large position sensitivity basing on the lateral photovoltaic effect in tin diselenide films

Abstract

Layered tin diselenide (SnSe2) is of high interest to material scientists because it is an n-type semiconductor with a narrow bandgap. In this letter, we prepared single-phase SnSe2 films and investigated the lateral photovoltaic effect (LPE) in SnSe2/p-Si junctions. The XRD, XPS, and Raman spectra confirm that the SnSe2 film is of high quality. The LPE shows a linear dependence on the position of the laser spot. The observed position sensitivity is as high as 364.5 mV mm−1. The optical relaxation-time for the LPE is about 3.07 μs. The dependence of the LPE on laser power and laser wavelength suggest that the LPE originates from the photoelectric effect and not from the thermoelectric effect. The nonlinearly current-voltage curve on the surface of the SnSe2 film indicates that most of the laser-excited electrons diffuse laterally within the inversion layer at the SnSe2/p-Si interface. This results in a large LPE with a fast relaxation time. The self-power, fast optical relaxation time and large position sensitivity of the LPE opens new opportunities for optical position-sensitive detector of SnSe2.