Interfacial properties of MoS2 thin films grown on functional substrates

TL;DR

This study explores how different substrates influence defect formation and electronic properties in MoS2 thin films, highlighting the importance of substrate selection for device engineering.

Contribution

It provides a comprehensive analysis combining experimental and theoretical methods to understand substrate-induced defects in MoS2 on three key substrates.

Findings

SrTiO3 induces metallic behavior due to Ti interdiffusion.

Al2O3 causes sulfur-related defects leading to localized states.

SiC results in interface disorder and semiconducting resistivity.

Abstract

Interface chemistry and defect formation in MoS2 thin films grown on single crystal substrates critically determine the electronic structure of MoS2 and thus can strongly modify material functionality relevant for many applications, including electronics, optoelectronics, and energy related catalysis. We investigate MoS2 grown on three technologically relevant substrates, namely SrTiO3(111), c-axis Al2O3(0001) and 6H-SiC(0001). Experimental investigations by temperature dependent resistivity, photoemission spectroscopy and scanning transmission electron microscopy with coupled energy dispersive spectroscopy, with the support of theoretical calculation by Density Functional Theory, allow the identification of the substrate induced specific defects and their correlation with the electronic properties. Ti interdiffusion in SrTiO3/MoS2 generates donor like states near the Fermi level, leading to metallic transport. Al2O3/MoS2 exhibits a high density of sulfur related defects that introduce localized states and yield nearly temperature independent conductivity. SiC/MoS2 exhibits significant interface disorder resulting in a semiconducting temperature dependent resistivity, yet deviating from the ideal bulk like behavior. These results demonstrate how substrate choice governs defect formation and ultimately dominates the electronic behavior of MoS2 thin films, making the control of film substrate interactions essential for the engineering of new functional devices.