Planar p-n Junction Based on a TMDs/Boron Nitride Heterostructure

Transition metal dichalcogenides (TMDs) are attracting growing interest for their prospective application in electronic and optical devices. As a leading material in researches of two-dimensional (2D) electronics, although band structure is layer-dependent, the TMDs show ambipolar properties. While optically excited light emission has been widely investigated, study on electrically generated emission is still limited. Taking the advantage of its ambipolarity and presence of direct band-gap in monolayer, we developed an electrically driven light emitting device based on stacked 2D flakes to obtain sharp planar p-n junction in monolayer. Specifically, we have fabricated atomic-layer TMDs/boron nitride (BN) artificial heterostructures using stacked h-BN thin flake as a mask to partially cover the TMDs transistor channel allowing high-density hole accumulation (p-region) via localized exposure to gate-controlled accumulation of anions. Transport through the junction shows typical diode-like rectification current with accompanying strong and sharp light emission from the crystal edge of BN mask for the monolayer case.