Ultrathin silicon oxynitride layer on GaN for dangling-bond-free GaN/insulator interface

Low Threshold Voltage Shift in AlGaN/GaN MIS-HEMTs on Si Substrate Using SiNx/SiON as Composite Gate Dielectric

This study has demonstrated AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs) on Si substrates with a SiNx/SiON composite gate dielectric. The threshold voltage shift in the devices was investigated. The MIS-HEMTs with the SiNx/SiON composite gate dielectric exhibited superior threshold voltage uniformity and small threshold voltage hysteresis than the reference device with SiNx only gate dielectric. The variation of the device threshold voltage was mainly related to trapping process by the interface states, as confirmed by band diagrams of MIS-HEMTs at different gate biases. Based on frequency-dependent capacitance measurements, interface state densities of the devices with the composite and single gate dielectrics were extracted, where the former showed much smaller interface state density. These results indicate that the SiNx/SiON composite gate dielectric can effectively improve the device performance of GaN-based MIS-HEMTs and contribute to the development of high-performance GaN electronic devices.

Breaking the Controversy of the Electropolymerization of Pyrrole Mechanisms by the Effective Screening Medium Quantum Charged Model Interface

Several mechanisms for the electropolymerization of pyrrole have been proposed since the first report 40 years ago. However, none of them were consensual despite a range of assumptions. We simulated and explained the preliminary steps governing the electropolymerization of pyrrole in a charged model interface using first-principles molecular dynamics calculations to solve the problem. We have shown under these conditions that adjacent pyrrole molecules in water can react together, causing their electropolymerization at the interface with a biased platinum electrode in anodic oxidation. In this work, the effective screening medium method that prevents energy divergence of the system was applied to different configurations of pyrrole, water, and electrolyte molecules to best screen the phase space. Furthermore, we worked on a Pt(100) electrode surface in an aqueous electrolyte to be as close as possible to the experimental conditions, MD taking the average of their different orientations.

A computational study on the electrified Pt(111) surface by the cluster model

A hemispherical cuboctahedral Pt₃₇ cluster is applied to study NO adsorption and reduction on the Pt(111) surface by using density functional theory.