Dopant activation process in Mg-implanted GaN studied by monoenergetic positron beam.

A process for activating Mg and its relationship with vacancy-type defects in Mg-implanted GaN were studied by positron annihilation spectroscopy. Mg ions were implanted with an energy of 10 keV, and the Mg concentration in the subsurface region (≤ 50 nm) was on the order of 10 cm. After the Mg-implantation, N ions were implanted to provide a 300-nm-deep box profile with a N concentration of 6 × 10 cm.

Interfacial Conductivity Enhancement and Pore Confinement Conductivity-Lowering Behavior inside the Nanopores of Solid Silica-gel Nanocomposite Electrolytes.

Solid nanocomposite electrolytes (nano-SCEs) that exhibit higher ionic conductivity than the individual confined electrolyte were investigated for high-performance solid-state batteries. Understanding the behavior of Li-ion conduction through the pores is important to design ideal nanoporous structures for nano-SCEs, which are composed of an ionic liquid electrolyte (ILE) in a highly porous (∼90%) silica matrix. To establish the relationship between the pore structure of the silica matrix and the ionic conductivity of the solid nanocomposite, the liquid electrolyte fraction was successfully extracted from the nano-SCE to reveal the fragile porous silica matrix.

Effects of ultra-high-pressure annealing on characteristics of vacancies in Mg-implanted GaN studied using a monoenergetic positron beam.

Vacancy-type defects in Mg-implanted GaN were probed by using a monoenergetic positron beam. Mg ions were implanted into GaN to obtain 0.3-μm-deep box profiles with Mg concentrations of 1 × 10 cm.

Effect of Free-Volume Hole Fraction on Dynamic Mechanical Properties of Epoxy Resins Investigated by Pressure-Volume-Temperature Technique.

Dynamic mechanical analysis experiments were carried out to investigate the mechanical properties of four types of chemically different epoxy resins. Pressure-volume-temperature (PVT) experiments were performed to determine the free-volume hole fraction () of each epoxy resin using the Simha-Somcynsky lattice-hole theory. Using the Williams-Landel-Ferry equation, the correlations between the relative hole fraction (1 - /, where is the hole fraction at a reference temperature ) and four typical parameters reflecting dynamic mechanical properties [storage modulus ('), loss modulus (″), damping factor (tanδ), and complex viscosity (|η*|)] were studied in the temperature range from (the glass transition temperature determined by PVT data) to + 100 °C.

Computational study of positron annihilation parameters for cation mono-vacancies and vacancy complexes in nitride semiconductor alloys.

We calculate positron annihilation parameters, namely the S and W parameters from the Doppler broadening spectroscopy and the positron lifetime [Formula: see text], for defect-free states as well as cation mono-vacancies and vacancy complexes in nitride semiconductor alloys AlGaN, InGaN and AlInN. The obtained distributions of these parameters differ from compound to compound. Especially, the S-W relation for InGaN is very different from that for AlGaN.