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The extremely high dv/dt of 4H-SiC insulated gate bipolar transistor (IGBT) becomes the major concern in its next-generation large-volume power conversion applications because severe electromagnetic interference (EMI) is induced. However, the root reason for its high dv/dt and the method of suppressing EMI have not been extensively investigated yet. In this paper, we proposed a novel physical model for SiC IGBT to identify the major limiting device design parameters of dv/dt during switching transients. The influences of SiC IGBT’s design parameters on its dv/dt and power dissipation are quantitatively analyzed by means of the physical model. Comparisons between the theoretical predictions and technology computer-aided design simulation results validate the physical model. The results on design optimization of a 18 kV n-channel SiC IGBT shows that 80% reduction of dv/dt and 60% reduction in turn-off power dissipation are achieved simultaneously without sacrificing its forward voltage drop.

A GaN-based pin neutron detector with a 6LiF conversion layer was fabricated, and can be used to detect thermal neutrons. Measurement of the electrical characteristic of the GaN-based pin neutron detector showed that the reverse leakage current of the neutron detector was reduced significantly after deposition of a 6LiF conversion layer on the detector surface. The thermal neutrons used in this experiment were obtained from an 241Am–Be fast neutron source after being moderated by 100-mm-thick high-density polyethylene. The experimental results show that the detector with 16.9-μm thick 6LiF achieved a maximum neutron detection efficiency of 1.9% at a reverse bias of 0 V, which is less than the theoretical detection efficiency of 4.1% calculated for our GaN neutron detectors.

We reported a method combining the gas–liquid interface method and inductively coupled plasma (ICP) to fabricate highly-ordered nanowire arrays on a 2 inch GaAs substrate. A large-area and highly-ordered SiO2 nanosphere monolayer was fabricated and the GaAs nanowire array was etched by ICP. The flow rates and ratios of the etching gases were studied. Finally, highly-ordered GaAs nanowire arrays with high quality surface morphology were obtained with the volumetric flow rates at 9 sccm and 21 sccm for BCl3 and N2 gases, respectively. Reflectance of the samples was found to be consistently below 10%, the lowest being 3%.

Gallium arsenide (GaAs) nanowire array (NWA) photocathodes have unique electrical and optical properties. Based on studies about photon absorption, band structure, and electron transport properties of GaAs nanowire, a photoemission model for GaAs NWA photocathodes is established. According to the model, we simulate and analyze the photocurrent, spectral response, and absorption properties of ordered GaAs NWA photocathodes. The results present a very interesting phenomenon; the photocurrent and spectral response peak at incident angles of 20° and 30°, respectively. These special properties of NWA cathodes differentiate them from their thin film counterparts. We also analyze the effects of nanowire length and diameter on the photocurrent of NWA cathodes, and find the optimum height of the nanowires is 10 μm. This study shows that NWAs exhibit higher absorbance and excellent charge transport. Thus, GaAs NWA photocathodes are excellent candidates for electron sources.