Centimeter-scale synthesis of ultrathin layered MoO3 by van der Waals epitaxy

TL;DR

This paper presents a simple atmospheric pressure van der Waals epitaxy method for large-scale synthesis of ultrathin MoO3 layers, enabling high-quality, centimeter-scale crystals suitable for optoelectronic applications.

Contribution

It introduces a novel, low-cost synthesis technique for ultrathin MoO3 with high quality and large area, and demonstrates its application in optoelectronic devices.

Findings

Successfully synthesized centimeter-scale ultrathin MoO3 layers.

Demonstrated high responsivity of 30 mA/W in UV photodetectors.

Showed MoO3's weak interlayer interaction leading to monolayer-like properties.

Abstract

We report on the large-scale synthesis of highly oriented ultrathin MoO3 layers using a simple and low-cost atmospheric pressure by van der Waals epitaxy growth on muscovite mica substrates. By this method we are able to synthetize high quality centimeter-scale MoO3 crystals with thicknesses ranging from 1.4 nm (two layers) up to a few nanometers. The crystals can be easily transferred to an arbitrary substrate (such as SiO2) by a deterministic transfer method and extensively characterized to demonstrate the high quality of the resulting crystal. We also study the electronic band structure of the material by density functional theory calculations. Interestingly, the calculations demonstrate that bulk MoO3 has a rather weak electronic interlayer interaction and thus it presents a monolayer-like band structure. Finally, we demonstrate the potential of this synthesis method for optoelectronic applications by fabricating large-area field-effect devices (10 micrometers by 110 micrometers in lateral dimensions), finding responsivities of 30 mA/W for a laser power density of 13 mW/cm2 in the UV region of the spectrum and also as an electron acceptor in a MoS2-based field-effect transistor.