A novel SiC Schottky barrier diode (SBD) hydrogen gas sensor with trench-insulator structure was proposed in this paper. A physical model is built for this hydrogen sensor based on 4H-SiC SBD thermionic emission theory, tunneling effect of carriers, adsorption/desorption principle of hydrogen and modulation effects of Schottky barrier height. Use Silvaco TCAD, the semiconductor simulation software, to analyze SBDs with trench-insulator layer and to compute current-voltage characteristics at different temperature, hydrogen concentration and trench width under forward bias. The temperature and hydrogen concentration affect the I–V characteristics of the devices by changing the Schottky barrier height. Compared with normal metal-silicon carbide and metal-insulator-silicon carbide devices at 573 K in terms of on-off voltage, current resolution, response speed, and stability, the trench-insulator hydrogen sensor showed good performance. Relationship between device characteristics and trench width was researched using the above model. Trench width has an opposite effect on sensor resolution and sensitivity.

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This paper presents a new rear-triggered vanadium-compensated 4H silicon carbide (4H-SiC) photoconductive semiconductor switch (PCSS) with aluminum nitride (AlN) anti-reflection coating on the back of PCSS device. Characteristics of PCSS are investigated by using semiconductor device simulation software Silvaco-TCAD. The switch substrates were doped with vanadium to make the substrates highly insulated. The on-state performance of the photoconductive switch was tested under pulsed light conditions with a wavelength of 532 nm and an optical power density of 6.8 MW/cm2 at a bias voltage of 2 kV. And the bias voltage was increased from 0 V to 10 kV in the absence of light trigger conditions, and its off-state characteristics were tested. Results show that the electric field strength between electrodes can be reduced by using rear-triggered structure, the switch breakdown voltage is over 80 kV DC, the maximum transient current is about 137 A, and the tail current almost disappears when the pulse light is turned off. In addition, the breakdown voltage of the rear-triggered PCSS to be higher than that of the front-triggered one. After adding AlN anti-reflection coating on the switch, the maximum transient of the switch and the optical utilization efficiency of laser energy are significantly improved, the maximum transient current of the switch was greatly improved from137 A to 150 A, which was increased by about 9.4 %. In addition, the effects of substrate thickness and optical power density on the switching performance were evaluated.