First-Principles Simulation on Piezoresistivity in Alpha and Beta Silicon Carbide Nanosheets

We have simulated strain gauge factors in some n-type alpha and beta silicon carbide (SiC) nanosheet models on the basis of first-principles calculations. Our original procedure of simulating piezoresistive properties was applied to the two-dimensional system with a multivalley conduction-band structure. The calculated gauge factors of the 2H-SiC(0001) nanosheet model for the [1100] tensile strain are very small at room temperature, but the longitudinal gauge factor shows a significant negative value at high temperatures. In the simulation of the gauge factors of the 4H-, 6H-, and 3C-SiC(0001) models, negative longitudinal gauge factors and positive transverse ones are clearly given at room temperature, and they are in good proportion to 1/T. The piezoresistivity of the 2H-SiC(0001) model increases rapidly as temperature rises, and it is expected that n-type 2H-SiC(0001) nanosheet will be useful for future high-temperature sensor applications, owing to its piezoresistivity at high temperatures.