Influence of Stoichiometry on the Optical and Electrical Properties of Chemical Vapor Deposition Derived MoS${}_2$

Abstract

Ultrathin transition metal dichalcogenides (TMDCs) of Mo and W show great potential for digital electronics and optoelectronic applications. Whereas early studies were limited to mechanically exfoliated flakes, the large-area synthesis of 2D TMDCs has now been realized by chemical vapor deposition (CVD) based on a sulfurization reaction. Since then, the optoelectronic properties of CVD grown monolayer MoS${}_2$ have been heavily investigated, but the influence of stoichiometry on the electrical and optical properties has been largely overlooked. Here we systematically vary the stoichiometry of monolayer MoS${}_2$ during CVD via controlled sulfurization and investigate the associated changes in photoluminescence and electrical properties. X-ray photoelectron spectroscopy is employed to measure relative variations in stoichiometry and the persistence of MoO${}_x$ species. As MoS${}_{2-\delta }$ is reduced (increasing δ), the field-effect mobility of monolayer transistors increases while the photoluminescence yield becomes non-uniform. Devices fabricated from monolayers with the lowest sulfur content have negligible hysteresis and a threshold voltage of ~0 V. We conclude that the electrical and optical properties of monolayer MoS${}_2$ crystals can be tuned via stoichiometry engineering to meet the requirements of various applications.

References in corpus (8)

• Ultrahigh electron mobility in suspended graphene
• Synthesis of Large-Area MoS2 Atomic Layers with Chemical Vapor Deposition
• Symmetry-dependent phonon renormalization in monolayer MoS2 transistor
• Channel Length Scaling of MoS2 MOSFETs
• Vapor-Solid Growth of High Optical Quality MoS2 Monolayers With Near-Unity Valley Polarization
• Optical identification of atomically thin dichalcogenide crystals
• Electrical property tuning via defect engineering of single layer MoS2 by oxygen plasma
• Large Thermoelectricity via Variable Range Hopping in Chemical Vapor Deposition Grown Single-layer MoS2

Cited by in corpus (6)

• Solvent Exfoliation of Electronic-Grade, Two-Dimensional Black Phosphorus
• Gate-tunable Memristive Phenonmena Mediated by Grain Boundaries in Single Layer MoS2
• Ultrafast Exciton Dissociation and Long-Lived Charge Separation in a Photovoltaic Pentacene MoS2 van der Waals Heterojunction
• In Situ Thermal Decomposition of Exfoliated Two-Dimensional Black Phosphorus
• Intrinsic Electrical Transport and Performance Projections of Synthetic Monolayer MoS2 Devices
• Tuning the Threshold Voltage of MoS2 Field-Effect Transistors via Surface Treatment