First-order piezoresistance coefficients in silicon crystals

The first-order piezoresistance coefficients (pi(11), pi(12)) and (pi(11), pi(12), pi(44)) are calculated for silicon crystals with electron and hole conductivities, respectively. Presented here analytical expressions for the piezoresistance coefficients are obtained for the first time with the account of a dependence of relaxation time tau of charged carriers on elastic strain. Our calculation of the piezoresistance coefficients in p-type silicon was carried out within the framework of the two-band anisotropic model taking into account the conventional dispersion law of light and heavy holes. For silicon crystals with electron conductivity it was obtained a good agreement between the calculated and experimental data in a wide range of impurity concentration (10(16)-10(20) cm(-3)). For crystals with the hole conductivity the satisfactory quantitative agreement was obtained for low and medium levels of the impurity concentrations (less than or equal to3 x 10(18) cm(-3)) (C) 2004 Elsevier B.V. All rights reserved.