Optimized single-layer MoS field-effect transistors by non-covalent functionalisation.

Field-effect transistors (FETs) with non-covalently functionalised molybdenum disulfide (MoS2) channels grown by chemical vapour deposition (CVD) on SiO2 are reported. The dangling-bond-free surface of MoS2 was functionalised with a perylene bisimide derivative to allow for the deposition of Al2O3 dielectric. This allowed the fabrication of top-gated, fully encapsulated MoS2 FETs.

Highly Sensitive Electromechanical Piezoresistive Pressure Sensors Based on Large-Area Layered PtSe Films.

Two-dimensional (2D) layered materials are ideal for micro- and nanoelectromechanical systems (MEMS/NEMS) due to their ultimate thinness. Platinum diselenide (PtSe), an exciting and unexplored 2D transition metal dichalcogenide material, is particularly interesting because its low temperature growth process is scalable and compatible with silicon technology. Here, we report the potential of thin PtSe films as electromechanical piezoresistive sensors.

Wide Spectral Photoresponse of Layered Platinum Diselenide-Based Photodiodes.

Platinum diselenide (PtSe) is a group-10 transition metal dichalcogenide (TMD) that has unique electronic properties, in particular a semimetal-to-semiconductor transition when going from bulk to monolayer form. We report on vertical hybrid Schottky barrier diodes (SBDs) of two-dimensional (2D) PtSe thin films on crystalline n-type silicon. The diodes have been fabricated by transferring large-scale layered PtSe films, synthesized by thermally assisted conversion of predeposited Pt films at back-end-of-the-line CMOS compatible temperatures, onto SiO/Si substrates.

High-Performance Hybrid Electronic Devices from Layered PtSe Films Grown at Low Temperature.

Layered two-dimensional (2D) materials display great potential for a range of applications, particularly in electronics. We report the large-scale synthesis of thin films of platinum diselenide (PtSe), a thus far scarcely investigated transition metal dichalcogenide. Importantly, the synthesis by thermally assisted conversion is performed at 400 °C, representing a breakthrough for the direct integration of this material with silicon (Si) technology.

Understanding and optimising the packing density of perylene bisimide layers on CVD-grown graphene.

The non-covalent functionalisation of graphene is an attractive strategy to alter the surface chemistry of graphene without damaging its superior electrical and mechanical properties. Using the facile method of aqueous-phase functionalisation on large-scale CVD-grown graphene, we investigated the formation of different packing densities in self-assembled monolayers (SAMs) of perylene bisimide derivatives and related this to the amount of substrate contamination. We were able to directly observe wet-chemically deposited SAMs in scanning tunnelling microscopy (STM) on transferred CVD graphene and revealed that the densely packed perylene ad-layers adsorb with the conjugated π-system of the core perpendicular to the graphene substrate.

Direct Observation of Degenerate Two-Photon Absorption and Its Saturation in WS2 and MoS2 Monolayer and Few-Layer Films.

The optical nonlinearity of WS2 and MoS2 monolayer and few-layer films was investigated using the Z-scan technique with femtosecond pulses from the visible to the near-infrared range. The nonlinear absorption of few- and multilayer WS2 and MoS2 films and their dependences on excitation wavelength were studied. WS2 films with 1-3 layers exhibited a giant two-photon absorption (TPA) coefficient as high as (1.

Heterojunction hybrid devices from vapor phase grown MoS2.

We investigate a vertically-stacked hybrid photodiode consisting of a thin n-type molybdenum disulfide (MoS2) layer transferred onto p-type silicon. The fabrication is scalable as the MoS2 is grown by a controlled and tunable vapor phase sulfurization process. The obtained large-scale p-n heterojunction diodes exhibit notable photoconductivity which can be tuned by modifying the thickness of the MoS2 layer.

Molybdenum disulfide/pyrolytic carbon hybrid electrodes for scalable hydrogen evolution.

The electrochemical generation of hydrogen fuel via the proton reduction in the Hydrogen Evolution Reaction (HER) in aqueous media is currently dependent on the use expensive noble metal catalysts for which alternatives must be sought. Molybdenum disulfide (MoS₂) has shown great promise as a suitable electrocatalyst in this regard. While many lab-scale experiments on the HER activity of this material have demonstrated its viability and explored some fundamental mechanistic features of HER at MoS₂, these experimental techniques are often ill-suited to large scale production of such electrodes.

Investigation of the interfaces in Schottky diodes using equivalent circuit models.

The metal-semiconductor contact is one of the most critical factors that determine the performance of semiconductor devices such as Schottky barrier diodes (SBDs). SBDs between conductive carbon thin films and silicon have attracted attention due to their high performance and potential low cost of fabrication. Here, we introduce impedance spectroscopy (IS) as a powerful technique to characterize such SBDs.

Chemically modulated graphene diodes.

We report the manufacture of novel graphene diode sensors (GDS), which are composed of monolayer graphene on silicon substrates, allowing exposure to liquids and gases. Parameter changes in the diode can be correlated with charge transfer from various adsorbates. The GDS allows for investigation and tuning of extrinsic doping of graphene with great reliability.

Carbon-silicon Schottky barrier diodes.

The simple fabrication of high-performance Schottky barrier diodes between silicon and conductive carbon films (C-Films) is reported. By optimizing the interface, ideality factors as low as n = 1.22 for pyrolytic photoresist films (PPF) have been obtained.