We investigated SiC-based hydrogen gas sensors with metal-insulator-semiconductor (MIS) structure for high temperature process monitoring and leak detection applications in fields such as the automotive, chemical and petroleum industries. In this work, a thin tantalum oxide (Ta2O5) layer was exploited with the purpose of sensitivity improvement, because tantalum oxide has good stability at high temperature with high permeability for hydrogen gas. Silicon carbide (SiC) was used as a substrate for high-temperature applications. We fabricated Pd/Ta2O5/SiC-based hydrogen gas sensors, and the dependence of their I-V characteristics and capacitance response properties on hydrogen concentrations were analyzed in the temperature range from room temperature to 500 °C. According to the results, our sensor shows promising performance for hydrogen gas detection at high temperatures.

The AgBiSe2–CuBiSe2 system shows band nestification at high temperatures, resulting in heavy DOS effective mass while preserving electron mobility.

Density functional calculations are performed to study the band structures of Bi2Te3-related binary (Bi2Te3, Sb2Te3, Bi2Se3, and Sb2Se3) and Sb/Se-doped ternary compounds and Bi2(Te1-ySey)3]. The band gap was found to be increased by Sb doping and to be monotonically increased by Se doping. In ternary compounds, the change in the conduction band structure is more significant as compared to the change in the valence band structure. The band degeneracy of the valence band maximum is maintained at 6 in binaries and ternaries.However, when going from Bi2Te3 to Sb2Te3 (Bi2Se3), the degeneracy of the conduction band minimum is reduced from 6 to 2(1). Based on the results for the band structures, we suggest suitable stoichiometries of ternary compounds for high thermoelectric performance.

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