Temperature-dependent photoresponse and transport properties of silicon MoS₂ Van der Waals heterostructure

Defects present in two-dimensional materials (2D) have a strong influence on the electrical and optical properties of devices based on 2D materials. Here, the temperature-dependent electronic transport and photoresponse of a silicon-MoS₂ p-n junction heterostructure are studied to understand the effect of defects, and a method of improving the photoresponse is demonstrated. The temperature-dependent I-V characteristics suggest the presence of a space charge limited transport with exponentially distributed trap states. The temperature dependence of ideality factor and intensity-dependent photoresponse also elucidate the nature of defects. The defects present in the heterostructure can cause recombinations diminishing the photoresponse and severely degrading the optoelectronic properties. A significant enhancement in photoresponse by reducing the recombination centers can be obtained by altering the dielectric environment. The study shows that for a particular dielectric, the enhancement is more prominent towards low temperatures. The low-frequency noise is observed to decrease with an increase in temperature and the dielectric medium suppressed the noise levels in these devices. Insights from this study would help in designing and improving the optoelectronic properties of low-dimensional optoelectronic devices.