Piezoresistivity of p-type heteroepitaxial diamond films on Si(100)

The piezoresistive effect of p-type heteroepitaxial diamond films was investigated. The films were grown by microwave plasma chemical vapor deposition and in situ boron doping was performed by cold ion implantation and rapid thermal annealing. The strain gauge was made by ion etching in an oxygen plasma. The gauge factor for the heteroepitaxial p-type diamond films at 100 microstrain was found to be 1200 at room temperature and was 980 even at 290 degrees C, greatly exceeding that of polycrystalline diamond films. The gauge factor did not change after pure acid treatment for up to 8 h, and little variation was found under ion irradiation. (C) 1998 Published by Elsevier Science S.A.