Piezoresistive Effect of Diamond Films Produced by dc Plasma CVD

The piezoresistive effect of polycrystalline p-type diamond films formed by dc plasma chemical vapour deposition has been investigated. The gauge factor is about 116 at 500 microstrains at room temperature, and strongly increases with increasing temperature, exceeding that of polycrystalline- and single-silicon. The origin of the piezoresistivity in boron doped polycrystalline diamond films may be ascribed to strain-induced shift of the boron acceptor level and grain boundaries.