  We investigate a two-dimensional (2D) heterostructure consisting of few-layer
direct bandgap ReS2, a thin h-BN layer and a monolayer graphene for application
to various electronic devices. Metal-insulator-semiconductor (MIS)-type devices
with two-dimensional (2D) van-der-Waals (vdW) heterostructures have recently
been studied as important components to realize various multifunctional device
applications in analogue and digital electronics. The tunnel diodes of
ReS2/h-BN/graphene exhibit light tuneable rectifying behaviours with low
ideality factors and nearly temperature independent electrical characteristics.
The devices behave like conventional MIS-type tunnel diodes for logic gate
applications. Furthermore, similar vertical heterostructures are shown to
operate in field effect transistors with a low threshold voltage and a memory
device with a large memory gate for future multifunctional device applications.
