Piezoresistive properties of polycrystalline silicon

Abstract

The piezoresistive gage factor of boron-doped CVD polysilicon films deposited with a boron-to-silicon ratio of 2×10−4–1.2 ×10−2 on an aluminum-oxide-insulated molybdenum substrate is found to be between 15 and 27. Annealing increases the gage factor. The higher the doping, the lower is the gage factor. Over the range 20–140 °C, the gage factor is not temperature sensitive if the boron-to-silicon ratio is higher than 2×10−3 during deposition. The temperature dependence increases as the doping concentration is decreased. Our analysis shows that the piezoresistive properties in polysilicon is mainly due to the bulk crystallites.

Electrical response to uniaxial tensile strain of a-Si:H TFTs fabricated on polyimide foils

“…Single-crystalline [8], polycrystalline [9], nanocrystalline [10], and amorphous silicon [11] change conductivity (resistivity) upon mechanical strain. This effect is called elastoconductivity or piezoresistance.…”

Influence of crystal defects on the piezoresistive properties of 3C–SiC

“…9,39 The observed changes in the directional dependence have been explained by misorientation of the individual crystallites, whereas a detailed explanation for the observed magnitude of the piezoresistive gauge factor as well as its dependence on temperature, carrier concentration, and grain size has not been reported yet. The piezoresistive properties of polcrystalline silicon have been found to be dominated by the piezoresistive behavior of the crystallites, however, the magnitude of the respective piezoresistive coefficients was found to be substantially smaller.…”

CMOS Force Sensor with Scanning Signal Process Circuit for Vertical Probe Card

“…Actually, there are two types of piezoresistance in polycrystalline silicon: p+ and n+, which have well known piezoresistance effects (the gauge factor is 30 (French, 2002;Seto, 1976)). We adopted polycrystalline silicon (poly1 layer n+) in the design of the sensor's piezoresistance.…”