Ga2O3 has been a subject of interest in research field with varying applications for current and future generation electronic devices. Due to its ultra-wide bandgap of 4.5–5.0 eV, extremely high BFOM of 3444, and other prominent characteristics relating to material properties, easy to mass-produce and economical, β-Ga2O3 finds applications in variety of electronics devices, power devices and optoelectronics devices. A comprehensive review of RF sputtered β-Ga2O3 films along with its properties, studies and applications are presented in this paper for the first time. Polymorphs of gallium oxide and crystal structure are discussed. Structural and chemical composition studies are reviewed with XRD and XPS. This review summarizes the recent progress in effects of sputtering parameters on film properties of Ga2O3. This review provides an in-depth analysis of mechanical, optical, film morphology, electrical properties of RF sputtered β-Ga2O3 films. The role of sputtering parameters such as substrate temperature, sputtering power, annealing temperatures and oxygen composition in the reactive sputtering for crystallinity are discussed. Furthermore, doping elements effects on bandgap changes are reported.

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The intrinsically anisotropic crystallinity of two-dimensional (2D) transition metal dichalcogenide (2D TMD) layers enables a variety of intriguing material properties which strongly depend on the physical orientation of constituent 2D layers. For instance, 2D TMDs with vertically-aligned layers exhibit numerous dangling bonds on their 2D layer edge sites predominantly exposed on the surface, projecting significantly improved physical and/or chemical adsorption capability compared to their horizontally-oriented 2D layer counterparts. Such property advantages can be further promoted as far as the material can be integrated onto unconventional substrates of tailored geometry/functionality, offering vast opportunities for a wide range of applications which demand enhanced surface area/reactivity and mechanical flexibility. Herein, we report a new form of 2D TMDs, i.e., three-dimensionally ordered 2D molybdenum disulfide (2D MoS2) with vertically-aligned layers integrated on elastomeric substrates and explore their tunable multi-functionalities and technological promise. We grew large-scale (>2 cm2) vertically-aligned 2D MoS2 layers using a three-dimensionally patterned silicon dioxide (SiO2) template and directly transferred/integrated them onto flexible polydimethylsiloxane (PDMS) substrates by taking advantage of the distinguishable water-wettability of 2D MoS2vs. SiO2. The excellent structural integrity of the integrated vertical 2D MoS2 layers was confirmed by extensive spectroscopy/microscopy characterization. In addition, the stretch-driven unique tunability of their optical and surface properties was also examined. Moreover, we applied this material for flexible humidity sensing and identified significantly improved (>10 times) sensitivity over conventionally-designed horizontal 2D MoS2 layers, further confirming their high potential for unconventional flexible technologies.

Recent commercialization has increased the research interest in transparent conducting oxides like indium tin oxide being implemented in display technologies and sensors. A wide range of values (4.2-5 eV) for the work function of ITO films are reported in literature. In this paper, we present an approach to extract the work function of indium tin oxide films from MOSFET devices. RF sputtered indium tin oxide is used as a transparent gate electrode to fabricate n-MOSFET. For the fabrication of the MOSFET, a four-level mask is used. Electrical characterization is performed on these MOSFET devices. We obtained work function value in the range between 4.62-4.81 eV using this technique. © The Author Indium tin oxide (ITO) is highly conductive wide bandgap semiconductor and exhibits excellent light transmission characteristics in visible and infrared spectrum. 1 The high electrical conductivity is due to contribution of oxygen vacancies and substitutional tin (Sn). Due to these unique properties, they are used as passive elements such as transparent electrodes in light-emitting devices (LED), 2 solar cells 3 and liquid crystal displays. 4 ITO is also used in organic electroluminescent devices like organic-LED (OLED) as an anode or a hole-injecting electrode due to its characteristic high work function ( ). 5 The work function of ITO also plays a central role in determining the efficiency and performance of the OLEDs and organic photovoltaics (OPVs) through control of hole injection process. 6,7 ITO is commonly regarded as high work function electrode. In the past, ITO has been used as hole collecting electrode in OPVs, or hole injecting electrode in OLEDs. Currently, OPVs or OLEDs are gaining popularity for being implemented with an inverted structure for improved air stability. The work function of ITO is reduced to facilitate electron collection or injection in such inverted structures.In many such applications, the work function has a significant impact on the device performance as it affects the energy barrier height at the heterojunction interface. 8 Additionally, applications like thermionic emission and Schottky effect require work function to act as a critical factor to determine the amount of current that can be emitted from a hot cathode. 9,10 Furthermore, determination of work function is of great importance to understand wide range of surface phenomenon in numerous applications utilizing indium tin oxide films. Hence, the work function of ITO is of critical importance. Work function measurements are broadly divided into two categories, absolute and relative measurements. Relative measurements involve probing methods such as Kelvin probe method, which makes use of contact potential difference between the sample and the reference electrode. 11 Absolute measurements employ photoemission, thermionic emission, field emission etc, in order to eject the surface electrons and are extensively characterized to obtain the absolute work function values. The problems with these methods are that they are expensive and i...