Piezoresistive linearity analysis of polysilicon nanofilms deposited at different temperatures based on interstitial-vacancy model

From our previous investigations, polysilicon nano-films (PSNFs) shows large gauge factor (>30) and lower temperature coefficients of resistance and gauge factor at high doping concentration, comparing with the common polysilicon films. The films are suitable for high temperature piezoresistive sensors. In this paper, the PSNFs doped highly (2×10²⁰ cm^-3) were prepared by LPCVD at different deposition temperatures, and the following measurements of resistivity, gauge factor and linearity of the films were performed. Based on as-established interstitial-vacancy model of grain boundaries, the structure, piezoresistive properties and linearity of PSNFs were analyzed. The influence of residual hydrogen atoms in films was also taken into consideration. The model is proved to have good agreement with experiment results. Finally, it can be obtained that using the optimized deposition temperature (620°C) and high temperature annealing, the PSNFs containing fewer amorphous phases and residual hydrogen atoms had better piezoresistive linearity.