Rhenium disulfide (ReS) has attracted immense interest as a promising two-dimensional material for optoelectronic devices owing to its outstanding photonic response based on its energy band gap's insensitivity to the layer thickness. Here, we theoretically calculated the electrical band structure of mono-, bi-, and trilayer ReS and experimentally found the work function to be 4.8 eV, which was shown to be independent of the layer thickness. We also evaluated the contact resistance of a ReS field-effect transistor using a Y-function method with various metal electrodes, including graphene. The ReS channel is a strong n-type semiconductor, thus a lower work function than that of metals tends to lead to a lower contact resistance. Moreover, the graphene electrodes, which were not chemically or physically bonded to ReS, showed the lowest contact resistance, regardless of the work function, suggesting a significant Fermi-level pinning effect at the ReS/metal interface. In addition, an asymmetric Schottky diode device was demonstrated using Ti or graphene for ohmic contacts and Pt or Pd for Schottky contacts. The ReS-based transistor used in this study on the work function of ReS achieved the possibility of designing the next-generation nanologic devices.
limits the further downscaling of Si-based electronic devices. 2D layered materials have attracted significant attention as post-Si nanoelectronic materials owing to their intriguing properties such as atomic thickness, having no dangling bond in a surface, high surface-to-volume ratio, and immunity to the short-channel effect. [1] Among the various 2D materials, 2H transition metal dichalcogenides (TMDCs), represented by MoS 2 and WSe 2 , are promising candidates for next-generation semiconductor materials in a post-Si era. They have suitable energy bandgaps and excellent electrical and optoelectronic properties that can overcome the fundamental limitations of graphene, which has zero energy bandgap. [2] TMDCs have the chemical structure of MX 2 , where M is a transition metal and X is a chalcogen atom, and they present a versatile platform with unique characteristics that depend on the combination of atoms. [3] In particular, WSe 2 exhibits ambipolar characteristics with high carrier mobilities (≈250 cm 2 V −1 •s for electron and 270 cm 2 V −1 •s for hole) and a bandgap that can be tuned according to the thickness (1.2 eV for monolayer and 1.7 eV for bulk). [4] It has been utilized in various electronic and optoelectronic applications, such as volatile and non-volatile memory, transistors, and photodetectors. [5][6][7][8][9] Despite the desirable characteristics of 2D TMDCs, the performance of intrinsic 2D TMDC-based electronic devices is still limited by low carrier concentrations and high contact resistance. [10][11][12] Impurity doping is a useful strategy to address these limitations. In conventional Si-based complementary metal-oxide-semiconductor (CMOS) technology, substitutional doping methods using ion implantation have been used to obtain electron-dominant and hole-dominant transport. [13,14] However, the ion implantation technique is inadequate for atomically thin semiconductor materials because it is extremely challenging to control the stopping ranges within a few nanometers. Ambipolar semiconductors which can exploit electrons and holes simultaneously in one channel are expected to simplify the complex ion implantation and subsequent rapid thermal processes. [15] Moreover, the use of ambipolar 2D semiconductor materials facilitates a reduction in footprint, providing opportunities for further miniaturization. If the majority carrier of an ambipolar 2D semiconductor can be effectively controlled, a high-performance multi-mode homojunction nanodevice Doping of van der Waals layered semiconductor materials is an essential technique to realize their full potential for implementation in nanoelectronics.Herein, defect-engineered and area-selective n-doping of ambipolar multi-layer WSe 2 are demonstrated via Ar plasma treatment. The contact regions of the WSe 2 are exposed to a mild Ar plasma treatment to induce Se vacancy, while the channel region is protected by a hexagonal boron nitride. The results are systematically analyzed using structural and optical characterization methods, and the origin of the...
temperature, [ 7,8 ] ultrasound, [ 9,10 ] and electric [ 11,12 ] or magnetic fi elds. [ 13,14 ] However, studies on release control regulated by mechanical strain are less common. [15][16][17][18][19] This is despite the fact that there are many processes involving strain changes in the human body and other biological systems, such as compression in cartilage and bone, tendon and muscle tension, internal shear force in blood vessels, and external force applied to skin. [ 20 ] Patch-type release is a promising system that can respond to mechanical stimuli and be implanted in the body or mounted on human skin. [21][22][23][24] There have been several patch-type approaches to strain-regulated delivery in the past, many of which were based on mechanochemical changes [ 16,25,26 ] or on strain-responsive leakage from microcapsules, [ 18 ] hydrogels, [ 19,27 ] or reservoirs containing microchannels. [ 17 ] For precise release control over a long period of time, a reservoir-based release system with a microchannel is advantageous because the release rate is dependent on the dimensions of the outlet channel, which can be readily adjusted by simple lithographic techniques. Advanced patch-type release systems are expected to possess the on/off regulation for fi ne release control and the stretchability to incorporate body motions. Refi lling of the drug solution may help long-term use of the patch system. Currently, most systems in this category rely on pressure [15][16][17]19 ] as a release stimulus; however, strain is a more logical choice of stimulus than pressure for human body applications because many body motions (such bending, twisting, and stretching) involve large amounts of strain.This study suggests designs of stretchable refi llable patchtype systems in which the release is regulated by external strains. As a proof-of-concept, the system was made of an elastomer, poly(dimethylsiloxane) (PDMS). The reservoirs were connected through microchannels for fi ne control of the release rate. The decrease of the reservoir volume caused by external strain was predicted by nonlinear fi nite element method (FEM) calculations. Result and DiscussionThe strain-regulated patch in this study contains an array of uniformly sized spherical reservoirs located just below the top surface of a rubber substrate. PDMS was chosen as the Many stimulus-induced release systems have been studied for the smart control of drug delivery. Mechanical strain is rarely investigated as means of stimulation for these systems, despite the fact that there are many biological processes and human body motions that involve strain changes. In this study, a design for a stretchable reservoir-based patch-type release system is suggested. The reservoir made of an elastomer undergoes a decrease in volume when the system is deformed by bending and stretching. The response is predicted by fi nite element method modeling studies. The release rate of the reservoir is fi nely controlled by attaching elastic microchannels with different channel lengths. Because the ...
Dispersing the minuscule mass loading without hampering the high catalytic activity and long-term stability of a noble metal catalyst results in its ultimate efficacy for the electrochemical hydrogen evolution reaction (HER). Despite being the most efficient HER catalyst, the use of Pt is curtailed due to its scarcity and tendency to leach out in the harsh electrochemical reaction environment. In this study, we combined F-doped tin(IV) oxide (F-SnO 2 ) aerogel with Pt catalyst to prevent metallic corrosion and to achieve abundant Pt active sites (approximately 5 nm clusters) with large specific surface area (321 cm 2 •g −1 ). With nanoscopic Pt loading inside the SnO 2 aerogel matrix, the as-synthesized hybrid F-SnO 2 @Pt possesses a large specific surface area and high porosity and, thus, exhibits efficient experimental and intrinsic HER activity (a low overpotential of 42 mV at 10 mA•cm −2 in 0.5 M sulfuric acid), a 22-times larger turnover frequency (11.2 H 2 •s −1 ) than that of Pt/C at 50 mV, and excellent robustness over 10,000 cyclic voltammetry cycles. The existing metal support interaction and strong intermolecular forces between Pt and F-SnO 2 account for the catalytic superiority and persistence against corrosion of F-SnO 2 @Pt compared to commercially used Pt/C. Density functional theory analysis suggests that hybridization between the Pt and F-SnO 2 orbitals enhances intermediate hydrogen atom (H*) adsorption at their interface, which improves the reaction kinetics.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.