Sub 20 meV Schottky barriers in metal/MoTe2 junctions

TL;DR

This study demonstrates the formation of ultra-low Schottky barriers in MoTe2-metal junctions, revealing Fermi level pinning effects and thermionic emission at low temperatures, with potential for tunable electronic applications.

Contribution

It provides experimental evidence of sub 20 meV Schottky barriers in MoTe2 contacts and analyzes Fermi level pinning and barrier tuning mechanisms.

Findings

Schottky barriers as low as 10 meV were observed.

Fermi level pinning occurs 0.14 eV above the valence band.

Thermionic emission detected between 40 K and 75 K.

Abstract

The newly emerging class of atomically-thin materials has shown a high potential for the realisation of novel electronic and optoelectronic components. Amongst this family, semiconducting transition metal dichalcogenides (TMDCs) are of particular interest. While their band gaps are compatible with those of conventional solid state devices, they present a wide range of exciting new properties that is bound to become a crucial ingredient in the future of electronics. To utilise these properties for the prospect of electronics in general, and long-wavelength-based photodetectors in particular, the Schottky barriers formed upon contact with a metal and the contact resistance that arises at these interfaces have to be measured and controlled. We present experimental evidence for the formation of Schottky barriers as low as 10 meV between MoTe2 and metal electrodes. By varying the electrode work functions, we demonstrate that Fermi level pinning due to metal induced gap states at the interfaces occurs at 0.14 eV above the valence band maximum. In this configuration, thermionic emission is observed for the first time at temperatures between 40 K and 75 K. Finally, we discuss the ability to tune the barrier height using a gate electrode.