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In this paper, a simulation model of p type PiN high voltage pulse open switch is established. The switch operates in "punch through" mode, with a 4 kA/cm2 cut-off current density and sub-nanosecond cut-off speed. The cut-off process of switch can be divided into three stages, that is, non-equilibrium carriers extraction stage, majority carriers drift stage and charging stage of junction capacitance by change of internal electric field and carrier concentration. Keeping injection current and cut-off current as 20 A and 40 A, the switch cut-off speed and "pedestal" voltage are reciprocally determined. Thus, optimizing the doping concentration and thickness of p layer is a valid solution for the actual system design. [ABSTRACT FROM AUTHOR]

The uniaxial strain-induced electronic structure variations in intrinsic and Al doped (3C-, 4H-) SiC are studied by using first-principle calculations. The main findings are summarized as follows: (I) the tensile strain leads to a structural transformation in Al doped 3C-SiC, which is signed by the total energy and lattice characteristics; (II) the band gap Eg modulation with large reductions is achieved by applying strains up to 2% in all compounds; (III) The high-symmetry points of valence band maximum and conduction band minimum in intrinsic and Al doped 4H-SiC show the abnormal characteristic under strain, corresponding to the maximum Eg as the strain is ∼-1%. These results suggest that the strain approach could be used to tune the electronic structures of SiC compounds. [ABSTRACT FROM AUTHOR]

Ferromagnetism can occur in wide-band gap semiconductors as well as in carbon-based materials when specific defects are introduced. It is thus desirable to establish a direct relation between the defects and the resulting ferromagnetism. Here, we contribute to revealing the origin of defect-induced ferromagnetism using SiC as a prototypical example. We show that the long-range ferromagnetic coupling can be attributed to the p electrons of the nearest-neighbor carbon atoms around the VSiVC divacancies. Thus, the ferromagnetism is traced down to its microscopic electronic origin. [ABSTRACT FROM AUTHOR]

In this article, we present a new configuration of opposed-contact vanadium-compensation semi-insulating (VCSI) 4H–SiC photoconductive semiconductor switch (PCSS) to reduce the input laser energy for operation. The configuration is made up of three parts: the PCSS with optical grating, the convex lens in front of PCSS, and the additional reflector behind PCSS. Periodic surface structures were fabricated on the VCSI 4H–SiC substrate by ultrafine femtosecond laser direct writing to etch optical gratings. The microstructure on the lower surface plays the role of reflection grating, so that the laser forms a specific distribution pattern and enhances the laser absorption. Experiments and simulations show that the triggering efficiency increased 3.7 times compared to PCSS without grating at 532 nm laser. And output voltage can reach 90 % of the input bias voltage. This SiC PCSS optical system significantly reduces the laser energy without reducing the electrodes spacing. • The designed SiC PCSS can increase the triggering efficiency by up to 3.7 times without increasing the laser energy. • Femtosecond laser direct writing technology can etch grating on the substrate of SiC PCSS. • Grating-type optical system can not only improve photoelectric conversion efficiency but also enhance integration level. [ABSTRACT FROM AUTHOR]