Enhancing performance of SnS2 based self-powered photodetector and photocatalyst by Na incorporation

Abstract

Sn and S are environmentally friendly elements that are abundant in nature. The SnS2 compound formed with these elements has intrinsic n-type electrical conductivity and a direct forbidden band gap of ∼ 2.2 eV. Therefore, it is a very promising compound for visible light optoelectronic applications. In this study, SnS2thin films were coated on p-Si substrates and pn heterojunction structures were obtained. By adding certain amounts of Na element to SnS2, the photosensitivity of the heterojunction devices increased tremendously and reached a high value of 3.2x104 under zero bias condition. It was observed that the prepared devices had excellent speeds and stability with rise and decay times of as low as 28 ms and 23 ms. Moreover, the devices were found to be sensitive to visible light even at ultra-low light intensity of ∼ 0.3 μW/cm2. Furthermore, the responsivity and specific detectivity values of the prepared photodetectors reach very high values of 11 A/W and 8.4x1013 Jones at this low light intensity. The NEP value drops to a low level of 2.7x10-15 WHz -1/2. In addition, the photocatalytic properties of Na-doped and undoped SnS2 compound were also examined under visible LED light. Compared to undoped samples, photocatalytic efficiency increased by ∼ 42% in Na-doped SnS2 thin films. The findings clearly reveal that Na improves both photodetector device performance and the photocatalytic effect of the SnS2 semiconductor.