Optoelectronic switch based on intrinsic dual Schottky diodes in ambipolar MoSe$_2$ field-effect transistors

TL;DR

This paper reports a novel light-induced diode-like response in multilayer MoSe₂ transistors, controllable by gate voltage, which could serve as an alternative optoelectronic switch and photovoltaic device.

Contribution

It introduces a new optoelectronic effect in MoSe₂ transistors caused by asymmetric Schottky barriers, with potential for technological applications.

Findings

Light-induced diode-like response observed in MoSe₂ transistors

Gate voltage controls current rectification direction

Potential for enhanced photovoltaic efficiency with barrier asymmetry

Abstract

Here, we report the observation of a hitherto unreported optoelectronic effect, namely a light-induced diode-like response in multi-layered MoSe$_2$ field-effect transistors whose sense of current rectification is controllable through a gate voltage. We argue, through numerical simulations, that this behavior results from the difference in the size of the Schottky barriers between drain and source metal contacts. Each barrier can be modeled as a Schottky diode but with opposite senses of current rectification between them, with the diode response resulting from the light induced promotion of photo-generated carriers across the smaller barrier. The back gate voltage controls the sense of current rectification by modulating the relative amplitude between them. This effect, which gives rise to a novel type of optoelectronic switch, also yields a photovoltaic response. Hence, it could provide an alternative to PN-junctions when harvesting photovoltaic currents from transition metal dichalcogenides. We argue that the photovoltaic efficiency associated to this effect could be increased by just increasing the relative asymmetry between both Schottky barriers. We also suggest that this new electro-optical effect has potential for technological applications.