Achieving tunability of two dimensional (2D) transition metal dichalcogenides (TMDs) functions calls for the introduction of hybrid 2D materials by means of localized interactions with zero dimensional (0D) materials. A metal-semiconductor interface, as in gold (Au) - molybdenum disulfide (MoS2), is of great interest from the standpoint of fundamental science as it constitutes an outstanding platform to investigate plasmonic-exciton interactions and charge transfer. The applied aspects of such systems introduce new options for electronics, photovoltaics, detectors, gas sensing, catalysis, and biosensing. Here we consider pristine MoS2 and study its interaction with Au nanoislands, resulting in local variations of photoluminescence (PL) in Au-MoS2 hybrid structures. By depositing monolayers of Au on MoS2, we investigate the electronic structure of the resulting hybrid systems. We present strong evidence of PL quenching of MoS2 as a result of charge transfer from MoS2 to Au: p-doping of MoS2. The results suggest new avenues for 2D nanoelectronics, active control of transport or catalytic properties.

We demonstrate that the electrical property of a single layer molybdenum disulfide (MoS 2 ) can be significantly tuned from semiconducting to insulating regime via controlled exposure to oxygen plasma. The mobility, on-current and resistance of single layer MoS 2 devices were varied up to four orders of magnitude by controlling the plasma exposure time. Raman spectroscopy, X-ray photoelectron spectroscopy and density functional theory studies suggest that the significant variation of electronic properties is caused by the creation of insulating MoO 3 -rich disordered domains in the MoS 2 sheet upon oxygen plasma exposure, leading to an exponential variation of resistance and mobility as a function of plasma exposure time. The resistance variation calculated using an effective medium model is in excellent agreement with the measurements. The simple approach described here can be used for the fabrication of tunable two dimensional nanodevices on MoS 2 and other transition metal dichalcogenides.

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The present study explores the structural, optical (photoluminescence (PL)), and electrical properties of lateral heterojunctions fabricated by selective exposure of mechanically exfoliated few layer two-dimensional (2D) molybdenum disulfide (MoS2) flakes under oxygen (O2)-plasma. Raman spectra of the plasma exposed MoS2 flakes show a significant loss in the structural quality due to lattice distortion and creation of oxygen-containing domains in comparison to the pristine part of the same flake. The PL mapping evidences the complete quenching of peak A and B consistent with a change in the exciton states of MoS2 after the plasma treatment, indicating a significant change in its band gap properties. The electrical transport measurements performed across the pristine and the plasma-exposed MoS2 flake exhibit a gate tunable current rectification behavior with a rectification ratio up to 1.3  ×  10(3) due to the band-offset at the pristine and plasma-exposed MoS2 interface. Our Raman, PL, and electrical transport data confirm the formation of an excellent lateral heterojunction in 2D MoS2 through its bandgap modulation via oxygen plasma.

The ability to modify the band structure of a semiconducting material via doping or defect engineering is of significant importance for the development of many novel applications in emerging nanoelectronics. Here, we show that the electronic transport properties of molybdenum disulfide (MoS 2 ) field effect transistors of various layer thicknesses (up to 8 layers) can be tailored via control exposure to oxygen plasma. We demonstrate that all the samples can be turned into complete insulators with increasing plasma exposure time and that the time required to turn the samples to complete insulators depends on the number of layers (L). We also found that the variation of mobility (μ) with plasma time (t) for all samples can be collapsed onto one curve and that μ follows a relation μ/L ≈ exp(−φt/L) where φ = μ/ μ, and μ̇is the time derivative of μ. X-ray photoelectron spectroscopy data show that MoO 3 defected regions were created by oxygen plasma and that the amount of MoO 3 increases with plasma time. Our study suggest that the energetic oxygens from the plasma not only interacts with the surface atoms but also propagate deep inside the layers to create MoO 3 defects in the MoS 2 , the transport properties of which can be described as an effective medium semiconductor with a bandgap higher than MoS 2 .