Low-field mobility and piezoresistivity of holes in germanium and silicon

A theoretical calculation of the low-field mobility and piezoresistance coefficients of holes in germanium and silicon is carried out incorporating all relevant details of the band structure. The scattering have been limited to acoustic and optical phonons and ionized-impurity and is described by the deformation potentials a, b, d and d₀. Values of the piezoresistance coefficients are calculated using matrix 6×6 expressions for the strain dependent energy-wave vector relations of the valence bands and the known deformation potentials. The calculated values of the first-order piezoresistance coefficients are found to agree fairly well with the experimental data