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Valley filter is a promising device for producing valley polarized current in graphene-like two-dimensional honeycomb lattice materials. The relatively large spin–orbit coupling in silicene contributes to remarkable quantum spin Hall effect, which leads to distinctive valley-dependent transport properties compared with intrinsic graphene. In this paper, quantized conductance and valley polarization in silicene nanoconstrictions are theoretically investigated in quantum spin-Hall insulator phase. Nearly perfect valley filter effect is found by aligning the gate voltage in the central constriction region. However, the valley polarization plateaus are shifted with the increase of spin–orbit coupling strength, accompanied by smooth variation of polarization reversal. Our findings provide new strategies to control the valley polarization in valleytronic devices.

Fundamentals of current transports of the NiJAu/AIGaN/GaN HEMTs have been studied under the temperature between 27"C and 250"C. It's found that the maximum drain-source current (IDS) decreases with rising temperature, and the temperature dependent of IDS has a negative coefficient of -O.314mAlmm ·°C. The decrease in mobility is considered to be the main cause of this deterioration. It's also found that a rise in temperature accompanies an increase in barrier height and a decrease in ideality factor. The remarkable finding is that reverse leakage current increases first and then decreases with rising temperature.