Centimeter-Scale Synthesis of Ultrathin Layered MoO₃ by van der Waals Epitaxy

Abstract

This is the post-peer reviewed version of the following article: A.J. Molina-Mendoza et al. "Centimeter-scale synthesis of ultrathin layered MoO3 by van der Waals epitaxy" Chem. Mater., 2016, 28 (11) ABSTRACTWe report on the large-scale synthesis of highly oriented ultrathin MoO3 layers using a simple and low-cost atmospheric pressure, 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 be extensively characterized to demonstrate the high quality of the resulting crystal. We also study the electronic band structure of the material by density functional 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 µm by 110 µm in lateral dimensions), finding responsivities of 30 mA·W -1 for a laser power density of 13 mW·cm -2 in the UV region of the spectrum and also as an electron acceptor in a MoS2-based field-effect transistor.This is the post-peer reviewed version of the following article: A.J. Molina-Mendoza et al. "Centimeter-scale synthesis of ultrathin layered MoO3 by van der Waals epitaxy"

Structural and electronic properties of bulk and ultrathin layers of V2O5 and MoO3

“…The bulk MoO 3 orthorhombic phase, has indirect band-gap of 2.2 eV as recently validated by experimental absorption spectra and theoretical data from PBEsol-vdW-D2 mehtod. 6 In our PBE+U/D3/SOC calculations with U O = 5 eV we obtain an indirect band-gap of 1.88 eV, about ~15% lower than the experimental one. On the other hand, the direct band-gap at Г-point is ~3.0 eV, which is quite close to to the optical absorption measurements which report a value of ~3.0-3.3 eV for this oxide.…”

Systematic Study of Oxygen Vacancy Tunable Transport Properties of Few‐Layer MoO3−x Enabled by Vapor‐Based Synthesis

“…Due to the environmental sensitivity of 2D MoO 3 , device fabrication is difficult. As a result, transport properties of MoO 3 have only been reported in the published literature for thicknesses greater than 6 nm . An in situ low dose electron‐beam irradiation technique was developed to introduce oxygen vacancies controllably and quantifiably and to overcome these fabrication difficulties.…”

Landau levels in 2D materials using Wannier Hamiltonians obtained by first principles

“…It has an orthorhombic unit cell, with each Mo atom sitting in an octahedral environment of O atoms. It is an indirect gap semiconductor, even in the 2D form, with a gap between the conduction band at Γ and the valence band at M 77.…”