Analysis of Electrical Characteristics in 4H-SiC Trench-Gate MOSFETs with Grounded Bottom Protection p-Well Using Analytical Modeling

A new analytical model to analyze and optimize the electrical characteristics of 4H-SiC trench-gate metal-oxide-semiconductor field-effect transistors (TMOSFETs) with a grounded bottom protection p-well (BPW) was proposed. The optimal BPW doping concentration (NBPW) was extracted by analytical modeling and a numerical technology computer-aided design (TCAD) simulation, in order to analyze the breakdown mechanisms for SiC TMOSFETs using BPW, while considering the electric field distribution at the edge of the trench gate. Our results showed that the optimal NBPW obtained by analytical modeling was almost identical to the simulation results. In addition, the reverse transfer capacitance (Cgd) values obtained from the analytical model correspond with the results of the TCAD simulation by approximately 86%; therefore, this model can predict the switching characteristics of the effect BPW regions.

Effect of wall temperature on the kinetic energy transfer in a hypersonic turbulent boundary layer

The effect of wall temperature on the transfer of kinetic energy in a hypersonic turbulent boundary layer for different Mach numbers and wall temperature ratios is studied by direct numerical simulation. A cold wall temperature can enhance the compressibility effect in the near-wall region through increasing the temperature gradient and wall heat flux. It is shown that the cold wall temperature enhances the local reverse transfer of kinetic energy from small scales to large scales, and suppresses the local direct transfer of kinetic energy from large scales to small scales. The average filtered spatial convection and average filtered viscous dissipation are dominant in the near-wall region, while the average subgrid-scale flux of kinetic energy achieves its peak value in the buffer layer. It is found that the wall can suppress the inter-scale transfer of kinetic energy, especially for the situation of a cold wall. A strong local reverse transfer of fluctuating kinetic energy is identified in the buffer layer in the inertial range. Helmholtz decomposition is applied to analyse the compressibility effect on the subgrid-scale flux of kinetic energy. A strong transfer of the solenoidal component of fluctuating kinetic energy is identified in the buffer layer, while a significant transfer of the dilatational component of fluctuating kinetic energy is observed in the near-wall region. It is also shown that compression motions have a major contribution to the direct transfer of fluctuating kinetic energy, while expansion motions play a marked role in the reverse transfer of fluctuating kinetic energy.

Laser induced reverse transfer for microfabrication

Laser induced reverse transfer for microfabrication

Laser induced reverse transfer for microfabrication

Laser induced reverse transfer for microfabrication

Off the Beaten Path: Can Statewide Articulation Support Students Transferring in Nonlinear Directions?

Students who transfer between colleges risk losing credits and decreasing their chances of degree completion. Despite emerging evidence regarding the effectiveness of articulation agreements to address this challenge, it is unclear if these policies support nonlinear transfer pathways—including lateral transfer between 4-year colleges or reverse transfer to 2-year colleges. I use propensity score weighting to examine a statewide articulation agreement in Ohio that established universal credit acceptance for coursework affecting all transfers. Comparing students who completed universally transferrable courses with those who did not, I find no measurable difference in degree attainment among reverse transfers. But there is a positive association with bachelor's degree attainment among lateral transfers, which the findings suggest is related to academic major persistence.

Influence of TOPO and TOPO-CdSe/ZnS Quantum Dots on Luminescence Photodynamics of InP/InAsP/InPHeterostructure Nanowires

The passivation influence by ligands coverage with trioctylphosphine oxide (TOPO) and TOPO including colloidal CdSe/ZnS quantum dots (QDs) on optical properties of the semiconductor heterostructure, namely an array of InP nanowires (NWs) with InAsP nanoinsertion grown by Au-assisted molecular beam epitaxy on Si (111) substrates, was investigated. A significant dependence of the photoluminescence (PL) dynamics of the InAsP insertions on the ligand type was shown, which was associated with the changes in the excitation translation channels in the heterostructure. This change was caused by a different interaction of the ligand shells with the surface of InP NWs, which led to the formation of different interfacial low-energy states at the NW-ligand boundary, such as surface-localized antibonding orbitals and hybridized states that were energetically close to the radiating state and participate in the transfer of excitation. It was shown that the quenching of excited states associated with the capture of excitation to interfacial low-energy traps was compensated by the increasing role of the “reverse transfer” mechanism. As a result, the effectiveness of TOPO-CdSe/ZnS QDs as a novel surface passivation coating was demonstrated.

Фотодинамика переноса возбуждения носителями заряда в гибридной наносистеме InP/InAsP/InP

The results of processing the luminescence attenuation kinetics of an InP/InAsP/InP hybrid semiconductor nanostructure with deposited colloidal layers of CdSe/ZnS quantum dots (QD) under excitation at wavelengths of 532 and 633 nm and temperatures of 80 and 300 K. Such a nanostructure is characterized by a significant increase in the duration and intensity of the luminescence of the INASP nanostructure. The mechanism of increasing the luminescence duration is presumably associated with the interaction of the QD CdSe/ZnS-TORO colloid with the InP surface, which leads to the formation of new hybrid states in the band gap that are energetically close to the radiating state and are able to capture electrons, which in turn is compensated by the increasing role of the electron reverse transfer process, which leads to an increase in the duration of radiative recombination.