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Beta gallium oxide (β‐Ga2O3) has emerged as a highly promising semiconductor material with an ultrawide bandgap ranging from 4.5 to 4.9 eV for future applications in power electronics, optoelectronics, as well as gas and ultraviolet (UV) radiation sensors. Here, surface adsorption and air damping behavior of doubly clamped β‐Ga2O3 nanomechanical resonators are probed and systemically studied by measuring the resonance characteristics under different gas and pressure conditions. High responsivities of resonance to pressure are obtained by heating the devices up to 300 °C to induce an accelerated adsorption–desorption process. The initial surface conditions of the β‐Ga2O3 thin film play important roles in affecting the resonant behavior. UV ozone treatment proves effective in altering the initial surface conditions of β‐Ga2O3 nanosheets by eliminating physisorbed contaminants and filling oxygen vacancy defects residing on the surface, resulting in a consequential and discernible modification of the resonance behavior of β‐Ga2O3 nanomechanical resonators. The surface adsorption and desorption processes in β‐Ga2O3 demonstrate clear reversibility by exposing the UV treated β‐Ga2O3 to air. This study attains first‐hand information on how the surface conditions of β‐Ga2O3 affect its mechanical properties, and helps guide future development of transducers via β‐Ga2O3 nanoelectromechanical systems (NEMS) for pressure sensing applications, especially in harsh environments. [ABSTRACT FROM AUTHOR]

Wide bandgap semiconductor ZnO, GaN and InN nanowires have displayed the ability to detect many types of gases and biological and chemical species of interest. In this review, we give some recent examples of using these nanowires for applications in pH sensing, glucose detection and hydrogen detection at ppm levels. The wide bandgap materials offer advantages in terms of sensing because of their tolerance to high temperatures, environmental stability and the fact that they are usually piezoelectric. They are also readily integrated with wireless communication circuitry for data transmission. [ABSTRACT FROM AUTHOR]

Flexible GaN-based light-emitting diodes (LEDs) on polyethylene terephthalate (PET) substrates are demonstrated. The process uses commercial LEDs on patterned sapphire substrates, laser lift-off (LLO), wet etching for additional surface roughening, and mounting of the freestanding LED on a PET substrate. Electrical and optical properties from the free-standing LLO-LEDs mounted on the flexible PET substrates were characterized. The process is scalable to large wafer diameters. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

This article presents a discussion on the role of nanowire (NW) structures, prepared by reactive ion etching (RIE), in planar III‐nitride light emitting diodes (LEDs) for increasing the functionality, improving the crystalline quality, enhancing the quantum efficiency of radiative recombination, and improving the light extraction efficiency. The methods of NW fabrication by RIE, of suppressing the adverse effects of RIE‐related damage, and of incorporating air voids into the NWs are also discussed. Furthermore, metal nanoparticles producing localized surface plasmons and semiconductor quantum dots downconverting the wavelength of light emitted by LEDs are explored. [ABSTRACT FROM AUTHOR]

2D materials having a sharp interface and no dangling bonds allow conventional heterojunction devices to overcome their limitations. 2D materials based vertical double heterojunction bipolar transistors are demonstrated by Jihyun Kim and co‐workers in article number 1800745. High current amplification is achieved in a common‐emitter mode. The results are expected to extend the application field of heterojunction electronic devices based on various 2D materials. [ABSTRACT FROM AUTHOR]

The heterojunction bipolar transistor (HBT) differs from the classical homojunction bipolar junction transistor in that each emitter‐base‐collector layer is composed of a different semiconductor material. 2D material (2DM)‐based heterojunctions have attracted attention because of their wide range of fundamental physical and electrical properties. Moreover, strain‐free heterostructures formed by van der Waals interaction allows true bandgap engineering regardless of the lattice constant mismatch. These characteristics make it possible to fabricate high‐performance heterojunction devices such as HBTs, which have been difficult to implement in conventional epitaxy. Herein, NPN double HBTs (DHBTs) are constructed from vertically stacked 2DMs (n‐MoS2/p‐WSe2/n‐MoS2) using dry transfer technique. The formation of the two P–N junctions, base‐emitter, and base‐collector junctions, in DHBTs, was experimentally observed. These NPN DHBTs composed of 2DMs showed excellent electrical characteristics with highly amplified current modulation. These results are expected to extend the application field of heterojunction electronic devices based on various 2DMs. Double heterojunction bipolar transistors (DHBTs) are fabricated from vertically stacked 2D materials (2DMs). Vertical DHBTs show excellent electrical characteristics with highly amplified current modulation, which are comparable to those of commercialized III–V semiconductor HBTs. These works can be applied in fields of heterojunction electronic devices based on various 2DMs. [ABSTRACT FROM AUTHOR]