One-dimensional electron-optical-phonon interaction Hamiltonians in a rectangular quantum wire consisting of diatomic polar semiconductors are derived under the macroscopic dielectric continuum model. The scattering rates calculated in a GaAs square quantum wire show that when the quantum wire is free-standing in vacuum, the interaction by the surface-optical phonon modes is very strong and may dominate over other scattering processes, especially with dimensions of about 100 Å or less. When the wire is embedded in a polar semiconductor (AlAs to be specific), the scattering rates by the surface-optical phonon modes become generally smaller, but yet comparable to those by the confined longitudinal-optical modes as the wire dimension shrinks. A considerable decrease in the total scattering rate for optical phonons as a result of simple reduction in dimensionality is not observed in this study.

Variable-range-hopping through disl identified as the main off-state leakage m GaN vertical diodes on different substrates. of leakage current for vertical devices as dislocation density and electric field was der simulations, after careful calibration with ex literature data. Designed GaN vertical diode 2-4 orders of magnitude lower leakage supporting 3-5 times higher electric field, GaN lateral, Si and SiC devices.

Abstract-Conventional GaN vertical devices, though promising for high-power applications, need expensive GaN substrates. Recently, low-cost GaN-on-Si vertical diodes have been demonstrated for the first time. This paper presents a systematic study to understand and control the OFF-state leakage current in the GaN-on-Si vertical diodes. Various leakage sources were investigated and separated, including leakage through the bulk drift region, passivation layer, etch sidewall, and transition layers. To suppress the leakage along the etch sidewall, an advanced edge termination technology has been developed by combining plasma treatment, tetramethylammonium hydroxide wet etching, and ion implantation. With this advanced edge termination technology, an OFF-state leakage current similar to Si, SiC, and GaN lateral devices has been achieved in the GaN-on-Si vertical diodes with over 300 V breakdown voltage and 2.9-MV/cm peak electric field. The origin of the remaining OFF-state leakage current can be explained by a combination of electron tunneling at the p-GaN/drift-layer interface and carrier hopping between dislocation traps. The low leakage current achieved in these devices demonstrates the great potential of the GaN-on-Si vertical device as a new low-cost candidate for high-performance power electronics.Index Terms-Edge termination, GaN-on-Si vertical device, leakage control, leakage origin, power electronics.

Temperature- and electric field-dependent electron transport in 3C–, 4H–, and 6H–SiC has been calculated by the Monte Carlo technique. Due to the freezeout of deep donor levels the role of ionized impurity scattering in 6H–SiC is suppressed and the role of phonon scattering is enhanced, compared to 3C– and 4H–SiC. There are indications of impurity band formation for impurity concentrations exceeding 1019 cm−3. It is found that ionized impurity scattering along with the deep donor ionization is responsible for the temperature dependence of mobility anisotropy ratio. Electron effective masses and electron-phonon coupling constants have been deduced from the comparison of Monte Carlo simulation results with available experimental data on low-field electron mobility. The extracted model parameters are used for high-field electron transport simulations. The calculated velocity-field dependencies agree with experimental results. The saturation velocities in all three polytypes are close, but the transient velocity overshoot at high electric field steps is much more pronounced in 3C–SiC.