Molybdenum disulfide (MoS2) field effect transistors (FET) were fabricated on atomically smooth large-area single layers grown by chemical vapor deposition. The layer qualities and physical properties were characterized using high-resolution Raman and photoluminescence spectroscopy, scanning electron microscopy, and atomic force microscopy. Electronic performance of the FET devices was measured using field effect mobility measurements as a function of temperature. The back-gated devices had mobilities of 6.0 cm2/V s at 300 K without a high-κ dielectric overcoat and increased to 16.1 cm2/V s with a high-κ dielectric overcoat. In addition the devices show on/off ratios ranging from 105 to 109.

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High-quality organic and inorganic van der Waals (vdW) solids are realized using methylammonium lead halide (CH3 NH3 PbI3 ) as the organic part (organic perovskite) and 2D inorganic monolayers as counterparts. By stacking on various 2D monolayers, the vdW solids exhibit dramatically different light emissions. Futhermore, organic/h-BN vdW solid arrays are patterned for red-light emission.

We report on the electronic transport properties of single-layer thick chemical vapor deposition (CVD) grown molybdenum disulfide (MoS 2 ) field-effect transistors (FETs) on Si/SiO 2 substrates. MoS 2 has been extensively investigated for the past two years as a potential semiconductor analogue to graphene. To date, MoS 2 samples prepared via mechanical exfoliation have demonstrated field-effect mobility values which are significantly higher than that of CVD-grown MoS 2 . In this study, we will show that the intrinsic electronic performance of CVD-grown MoS 2 is equal or superior to that of exfoliated material and has been possibly masked by a combination of interfacial contamination on the growth substrate and residual tensile strain resulting from the high-temperature growth process. We are able to quantify this strain in the as-grown material using pre-and post-transfer metrology and microscopy of the same crystals. Moreover, temperature-dependent electrical measurements made on as-grown and transferred MoS 2 devices following an identical fabrication process demonstrate the improvement in field-effect mobility. V

As two-dimensional (2D) electronic devices continue to advance, the need for integrating high-quality, high-κ nanoscale dielectrics becomes more essential. Plasmaenhanced atomic layer deposition (PEALD) is a promising approach for depositing ultrathin dielectrics directly onto the surface of 2D materials. However, the mechanism for PEALD film growth on the van der Waals materials, along with the impact of the plasma process on structural and interfacial properties of 2D materials, has not been fully explored. In this work, we demonstrate the effects of the plasma process on monolayer, bilayer, and trilayer MoS 2 . Back-gated MoS 2 transistors of varying thickness were tested before and after ALD/PEALD HfO 2 , and it was verified that plasma damage does occur, predominantly in the surface layer of the MoS 2 , leading to significantly greater impact in monolayers. By increasing the thickness of the MoS 2 , the adverse effects of the plasma process are reduced appreciably. This observation is further supported by Raman and transmission electron microscopy analysis. In addition to providing information about defect generation and morphology, this study provides key insights into the charge transfer between HfO 2 and MoS 2 . Overall, this detailed analysis of the impact of the PEALD plasma process on MoS 2 contributes to the reliable integration of ultrathin, high-κ dielectrics in 2D devices.