Functional interlayer of In2O3 for transparent SnO2/SnS2 heterojunction photodetector

Abstract

Light signals are widely employed in communications, military, health and space exploration applications, driving demand for self-powered photodetectors and sensors. Generally, the built-in potential in the heterojunction interface facilitates self-powered operation. However, this interface often contains defect states due to lattice mismatch and large differences in work function, which increases the dark current even under zero bias condition. In this article, we report the design of a self-powered and transparent (˜47%) photodetector using a SnO2/SnS2 heterojunction. In addition, we successfully demonstrate a reduction in dark current (6.9–2.8 μA) with a simultaneous increase in photocurrent (11.6–14.7 μA) by introducing an In2O3 interlayer in the SnO2/SnS2 heterojunction, while maintaining the average transparency of ˜47%. In addition, the fabricated device exhibited high rise and fall times of 59 and 79 μs, respectively. An energy band diagram based on the material work functions illustrates the creation of two staggered gap (Type-II) heterojunctions due to the embedded In2O3 nanolayer. This feasible band alignment facilitates the smooth transport of the photogenerated charge carriers. The interlayer also aids lattice matching while reducing defect states in the interface. The interface engineering by using a nanoscale layer embedment would effectively facilitate the feature of photoelectric device without degrading device transparency. This clearly demonstrates that the functional use of interlayer strongly enhances the device performances to suggest the further possible improvement in the transparent optoelectronics.