γ-rays irradiation effects on dielectric properties of Ti/Au/GaAsN Schottky diodes with 1.2%N

Dielectric properties of As grown and irradiated Ti /Au/GaAsN Schottky diodes with 1.2%N are investigated using capacitance/conductance-voltage measurements in 90–290 K temperature range and 50–2000 kHz frequency range. Extracted parameters are interface state density, series resistance, dielectric constant, dielectric loss, tangent loss and ac conductivity. It is shown that exposure to γ-rays irradiation leads to reduction in effective trap density believed to result from radiation-induced traps annulations. An increase in series resistance is attributed to a net doping reduction. Dielectric constant (ε’) shows usual step-like transitions with corresponding relaxation peaks in dielectric loss. These peaks shift towards lower temperature as frequency decrease. Temperature dependant ac conductivity followed an Arrhenius relation with activation energy of 153 meV in the 200–290 K temperature range witch correspond to As vacancy. The results indicate that γ-rays irradiation improves the dielectric and electrical properties of the diode due to the defect annealing effect

Feature Papers in Electronic Materials Section

This book entitled "Feature Papers in Electronic Materials Section" is a collection of selected papers recently published on the journal Materials, focusing on the latest advances in electronic materials and devices in different fields (e.g., power- and high-frequency electronics, optoelectronic devices, detectors, etc.). In the first part of the book, many articles are dedicated to wide band gap semiconductors (e.g., SiC, GaN, Ga2O3, diamond), focusing on the current relevant materials and devices technology issues. The second part of the book is a miscellaneous of other electronics materials for various applications, including two-dimensional materials for optoelectronic and high-frequency devices. Finally, some recent advances in materials and flexible sensors for bioelectronics and medical applications are presented at the end of the book

Wide Bandgap Based Devices

Emerging wide bandgap (WBG) semiconductors hold the potential to advance the global industry in the same way that, more than 50 years ago, the invention of the silicon (Si) chip enabled the modern computer era. SiC- and GaN-based devices are starting to become more commercially available. Smaller, faster, and more efficient than their counterpart Si-based components, these WBG devices also offer greater expected reliability in tougher operating conditions. Furthermore, in this frame, a new class of microelectronic-grade semiconducting materials that have an even larger bandgap than the previously established wide bandgap semiconductors, such as GaN and SiC, have been created, and are thus referred to as “ultra-wide bandgap” materials. These materials, which include AlGaN, AlN, diamond, Ga2O3, and BN, offer theoretically superior properties, including a higher critical breakdown field, higher temperature operation, and potentially higher radiation tolerance. These attributes, in turn, make it possible to use revolutionary new devices for extreme environments, such as high-efficiency power transistors, because of the improved Baliga figure of merit, ultra-high voltage pulsed power switches, high-efficiency UV-LEDs, and electronics. This Special Issue aims to collect high quality research papers, short communications, and review articles that focus on wide bandgap device design, fabrication, and advanced characterization. The Special Issue will also publish selected papers from the 43rd Workshop on Compound Semiconductor Devices and Integrated Circuits, held in France (WOCSDICE 2019), which brings together scientists and engineers working in the area of III–V, and other compound semiconductor devices and integrated circuits

Recent advances in electronic and optoelectronic Devices Based on Two-Dimensional Transition Metal Dichalcogenides

Two-dimensional transition metal dichalcogenides (2D TMDCs) offer several attractive features for use in next-generation electronic and optoelectronic devices. Device applications of TMDCs have gained much research interest, and significant advancement has been recorded. In this review, the overall research advancement in electronic and optoelectronic devices based on TMDCs are summarized and discussed. In particular, we focus on evaluating field effect transistors (FETs), photovoltaic cells, light-emitting diodes (LEDs), photodetectors, lasers, and integrated circuits (ICs) using TMDCs

Atomically Thin Platinum-based Dichalcogenide Materials for Multifunctional Photo-sensitive Applications

Two-dimensional (2D) transition metal dichalcogenides (TMDs) are a distinct class of atomically thin materials assembled by weak van der Waals bonding. They exhibit 2D layer number-dependent bandgap tunability promising exciting applications in electronics and optoelectronics. Among them, there is a surge of interest in Platinum-based dichalcogenides (e.g., PtSe2 and PtTe2). 2D PtSe2 has a theoretically predicted carrier mobility of \u3e 1000 cm2/(Vs), at room temperature, which is higher than that of most 2D TMDs. Additionally, 2D PtSe2 exhibits a semiconducting to metallic transition with an increasing number of layers. 2D PtTe2 is highly metallic in its few- layer form and exhibits electrical conductivity of \u3e 106 S/m – superior to most of the previously reported 2D TMDs. These properties project the promise of Platinum-based dichalcogenides for photosensitive applications. This intrinsic superiority of Platinum-based dichalcogenides is improved further when they are merged with conventional three-dimensional (3D) semiconductors such as silicon (Si). We applied a novel chemical vapor deposition (CVD) technique to synthesize large-area 2D PtSe2 and 2D PtTe2 directly on various substrates with controlled 2D layer orientation and electronic property. With direct CVD synthesis of metallic 2D PtSe2 and PtTe2 on silicon (Si) wafer, we created 2D PtSe2/Si and 2D PtTe2/Si Schottky junction devices. We investigated their photovoltaic performance as well as viability as photodetectors in visible to mid-infrared (MIR) regimes. The PtTe2/Si photodetectors exhibit fast photoresponse time (~ 1µs) and high photodetectivity ( \u3e 1013 Jones) in visible light and display photocurrent up to 7µm wavelength regime. Finally, we extended the application of Platinum-based dichalcogenides into flexible opto- electronics by directly synthesizing Platinum-based dichalcogenides on thin Si wafer or polyimide substrates, owing to their low synthesis temperature. These studies are a part of a new paradigm shift of using Pt-based TMDs with unique optical, electrical, and mechanical properties in unique photosensitive devices

Impact of Proton and Neutron Irradiation on Carrier Transport Properties in GA2O3

This project studies the properties of minority charge carriers in beta gallium oxide (β -Ga2O3). The behavior of minority carriers is of high importance as it greatly affects conduction and consequently device performance. Cathodoluminescence (CL) spectroscopy and EBIC (Electron Beam Induced Current) are the main experimental techniques used to study minority carrier behavior. High energy radiation affects minority carrier properties through damage to the material and through the production of carrier traps that reduce the conductivity and mobility of the material. In this investigation, we study the effects of various kinds of high energy radiation on properties of minority carriers in silicon-doped β -Ga2O3. The thermal activation energy of the reference (non-irradiated) sample was 40.9 meV, which is ascribed to silicon-donors. CL measurements indicate a slightly indirect bandgap energy of 4.9 eV. Under 10 MeV proton irradiation, the thermal activation energies increase. This increase is attributable to high order defects and their influence on carrier lifetimes. Differentiating itself from other forms of radiation, neutron irradiation creates disordered regions in β - Ga2O3 as opposed to just point defects, resulting in the lowest carrier removal rate because of the lowest average non-ionizing energy loss. Measurements show that β -Ga2O3 is more resistant to radiation damage than some other wide bandgap semiconductors due to its higher displacement threshold energy, which is inversely proportional to the lattice constant

Solid Oxide Electrochemical Cells for High Temperature Hydrogen Production: Theory, Fabrication and Characterization

In this dissertation, the concept of water splitting using solid oxide photoelectrochemical cells (SOPCs) at high temperature was introduced and experimentally investigated. High temperature photoelectrochemical water splitting physically broadens the selection of potential applicable semiconductor materials and enables more visible sunlight absorption. This newly conceived concept provides a unique pathway for solar hydrogen production, as compared to conventional photoelectrochemical cells (PECs) that use wide band gap semiconductors in aqueous environments. The theoretical framework of SOPC was elaborated, followed by the experimental investigation to search for appropriate high temperature materials. Selected high temperature Schottky and p-n junction diodes, which were expected to be applicable to the photocatalytic/oxygen electrodes of SOPCs, were fabricated and evaluated. Their rectifying characteristics were characterized at elevated temperatures. Among those diodes, only LSM/TiO2 demonstrated acceptable rectifying properties up to 450 °C, indicating that such configuration may be applicable to the proposed SOPC. The further investigation was carried out on fabrication of the electrodes of SOPC and solid oxide fuel cell (SOFC) using fused deposition modeling (FDM), a technique of 3D printing. The goal was to directly print out ceramic substrates and eventually make porous electrodes. Ceramic filaments that consist of ceramic electrode materials and thermoplastics were fabricated in house. After experimenting many thermoplastics, Nylon 12 was identified as an ideal thermoplastic polymer to make composite ceramic filaments. The printouts were sintered in the furnace to burn out all the organics, leaving behind porous electrodes made of pure ceramics. The 3D printed cathodes on half SOFCs were evaluated and demonstrated comparable performance to conventional SOFCs using dip-coating method. Therefore, FDM provides a viable and low cost means to fabricate the porous electrodes of SOPC/SOFC