Effect of Dielectric Environmental on Optoelectronic Properties of Mixed-Dimensional van der Waals Heterostructures

We have developed a simple method of fabricating large-area MoS₂ monolayer devices. We will discuss the fabrication of various heterostructures using monolayer MoS₂ as one of the components. Due to the 2D nature of MoS_2, the coulomb screening is less effective and the electronic and optoelectronic properties of these heterostructures depend strongly on the local environment. We made mixed-dimensional van der Waals heterostructures by combining n-type MoS₂ monolayer with p-type silicon. These 2D-3D systems show interesting photoresponse properties. We observed that the photoresponse strongly depends on the surrounding dielectric environment and by tuning the dielectric contestant, one can enhance the photoresponse by several orders of magnitude. We will discuss how various characterization methods such as low-frequency noise, dielectric and transient photoresponse can be used to understand the charge transport mechanism of such systems.