Evaluation of p-Type 4H-SiC Piezoresistance Coefficients in (0001) Plane Using Numerical Simulation

A numerical simulation of p-type 4H-Silicon Carbide (4H-SiC) piezoresistance coefficients in (0001) plane evaluation is shown in this study. A 4H-SiC material has outstanding material characteristics of wide band-gap of 3.26 eV and high temperature robustness. However, many material properties of 4H-SiC material are still unknown, including piezoresistance coefficients. Piezoresistive effect is resistivity change when mechanical stress is applied to the material. Piezoresistance coefficients express the magnitude of this effect, important for designing a mechanical stress sensor. In this study, reported piezoresistance coefficients of p-type 4H-SiC in (0001) plane is evaluated based on numerical simulation. The simulated results of Gauge Factor (GF) values (determined by (ΔR/R)/ε (R is the resistance and ε is the strain of material)) well matched to the theoretical GF values (determined by πE (π is the piezoresistance coefficient and E is Young’s modulus of the material)), shows that reported piezoresistance coefficients are reliable. Also, the internal mappings of piezoresistive effect from the numerical simulation are shown, useful to understand piezoresistive effect which is difficult to see by experimental results.

Electronic State and Piezoresistivity Analysis of Zinc Oxide Nanowires for Force Sensing Devices

The piezoresistivity for force sensing in wurtzite-ZnO nanowires with [0001] orientation has been simulated on the basis of the first-principles calculations of model structures. According to the difference in wall structure, our devised nanowire models can be divided into three groups by their conductivities; no band-gap conducting models, direct band-gap semiconducting models, and indirect band-gap semiconducting models. The strain responses to carrier conductivity of n-or p-doped semiconducting wurtzite-ZnO[0001] nanowire models were calculated using band carrier densities and their corresponding effective masses derived from the one-dimensional band diagram by our original procedure for a small amount of carrier occupation. The conductivities of p-type direct band-gap models change drastically due to longitudinal uniaxial strain in the simulation: the longitudinal piezoresistance coefficient is 120 × 10–11 Pa–1 for p-type (ZnO)24 nanowire model with 1% compressive strain at room temperature.

The Design of AlGaN/GaN HEFT-Micro-Accelerometer and Temperature- Dependence Electrical Performance

In this paper, We use a novel principle to detect acceleration and report how I-V characteristics and piezoresistance coefficient of AlGaN/GaN HEFT-micro-accelerometer are affected by setting different temperatures. It is shown that saturation current of device would go down if the temperature goes up, which is about 0.028mA/°C, based on the research. However, the device can work well at the temperature range of -50°C to 50°C, which indicates that it can work safely in the larger temperature range.