We report on a GaN metal-oxide-semiconductor field-effect-transistor (MOSFET) using atomic-layer-deposited (ALD) Al2O3 as the gate dielectric. Compared to a GaN metal-semiconductor field-effect-transistor (MESFET) of similar design, the MOSFET exhibits several orders of magnitude lower gate leakage and near three times higher channel current. This implies that the ALD Al2O3/GaN interface is of ...

We report a detailed investigation of the structural and chemical characteristics of thin evaporated Al2O3 tunnel barriers of variable thickness grown onto single-layer graphene sheets. Advanced electron microscopy and spectrum-imaging techniques were used to investigate the Co/Al2O3/graphene/SiO2 interfaces. Direct observation of pinhole contacts was achieved using FIB cross-sectional lamellas...

Transition aluminas form a basis of important catalytic and catalytic support materials due to their unique surface acidity, high temperature structural stability, and their viability for synthesis as high surface area materials [1]. The origin of transition aluminas attractive properties has been extensively studied in the past 50+ years, but despite this effort, there are number of structural...

Alumina-rich iron ore is a widely existed polymetallic deposit in the nature, and it has a high comprehensive utilization value. Because the alumina and iron contents of alumina-rich iron ore vary from each other, there are many different measures and processes to recover iron and alumina from the various kinds of alumina-rich iron ore. In the blast furnace (BF) ironmaking process, the alumina ...

Multilayered hard coatings with a CrN matrix and an Al2O3, TiO2, or nanolaminate-Al2O3/TiO2 sealing layer were designed by a hybrid deposition process combined with physical vapor deposition (PVD) and atomic layer deposition (ALD). The strategy was to utilize ALD thin films as pinhole-free barriers to seal the intrinsic defects to protect the CrN matrix. The influences of the different sealing ...

Transformation of Al(NO3)3∙9H2O (upon heating in the range of 20-1200 °C) into blends of amorphous and crystalline boehmite (210-525 °C), amorphous alumina and crystalline γ-Al2O3 (850 °C), and crystalline α-Al2O3 (1100 °C) was analyzed using X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), infrared (IR) spectroscopy, thermogravimetry, and low-temperature nitro...

In this research work, airplane grade aluminum alloy substrate was coated by Al2O3/ TiO2 ceramic coatings in two different compositions as 50:50 and 87:13 using Flame spraying technique. The surface & cross-sectional morphological characterizations of the Al2O3/ TiO2 powders and coatings were performed by scanning electron microscopy (SEM). The microwave absorbing properties of coatings were ex...

We present surface properties of buffer films (AIN and GaN) and Al0.3Gao.zN/Al2O3-High Electron Mobility Transistor (HEMT) structures with/without AIN interlayer grown on High Temperature (HT)-AIN buffer/Al2O3 substrate and Al2O3 substrate. We have found that the GaN surface morphology is step-flow in character and the density of dislocations was about 10(8)-10(9) cm(-2). The AFM measurements a...

Based on density functional methods, we investigate the origin of variations in electronic structures and dielectric constants of representative alumina polymorphs. We consider the most stable -Al2O3 and three metastable phases of alumina, , , and -Al2O3. Computed energy gaps are found to be in the order of , which can be understood based on electrostatic potentials at specific lattice sites; w...

The utilization of the anodic TiO2 nanotube layers, with uniform Al2O3 coatings of different thicknesses (prepared by atomic layer deposition, ALD), as the new electrode material for lithium-ion batteries (LIBs), is reported herein. Electrodes with very thin Al2O3 coatings (∼1 nm) show a superior electrochemical performance for use in LIBs compared to that of the uncoated TiO2 nanotube layers. ...