Large-area Epitaxial Monolayer MoS2

TL;DR

This paper demonstrates the large-area epitaxial growth of high-quality monolayer MoS2 with controlled lattice orientation, enabling improved electronic and optoelectronic applications, including UV photodetectors and transistors.

Contribution

It reports a method for uniform, centimeter-scale monolayer MoS2 growth with controlled lattice orientation via epitaxial growth, reducing grain boundaries and enhancing material quality.

Findings

High-quality, large-area monolayer MoS2 achieved

Lattice orientation controlled through epitaxial growth

Enhanced mobility in transferred transistors

Abstract

Two-dimensional semiconductors such as MoS2 are an emerging material family with wide-ranging potential applications in electronics, optoelectronics and energy harvesting. Large-area growth methods are needed to open the way to the applications. While significant progress to this goal was made, control over lattice orientation during growth still remains a challenge. This is needed in order to minimize or even avoid the formation of grain boundaries which can be detrimental to electrical, optical and mechanical properties of MoS2 and other 2D semiconductors. Here, we report on the uniform growth of high-quality centimeter-scale continuous monolayer MoS2 with control over lattice orientation. Using transmission electron microscopy we show that the monolayer film is composed of coalescing single islands that share a predominant lattice orientation due to an epitaxial growth mechanism. Raman and photoluminescence spectra confirm the high quality of the grown material. Optical absorbance spectra acquired over large areas show new features in the high-energy part of the spectrum, indicating that MoS2 could also be interesting for harvesting this region of the solar spectrum and fabrication of UV-sensitive photodetectors. Even though the interaction between the growth substrate and MoS2 is strong enough to induce lattice alignment, we can easily transfer the grown material and fabricate field-effect transistors on SiO2 substrates showing mobility superior to the exfoliated material.