A theoretical calculation of the piezoresistivity and magnetoresistivity in p-type semiconducting diamond films

A theoretical study of the piezoresistivity and magnetoresistivity in p-type heteroepitaxial diamond films is presented, based on the Fuchs-Sondheimer thin-film theory and the valence band split-off model. The Boltzmann transport equation in the relaxation time approximation was solved and a mixed scattering by lattice vibrations, ionized impurities and surfaces was considered. The analytical expressions for the piezoresistive and magnetoresistive effects has been developed in a parallel-connection resistance model for the light-hole, the heavy-hole and the split-off bands. The calculated results are discussed and compared with experimental data. It is found that the self-spin interaction of the heavy holes could be related to stress. Moreover, a possible mechanism is presented to explain the fact that the magnetoresistivity of the p-type heteroepitaxial diamond films is greater than that of the diamond bulk.