Analysis of the piezoresistive effect in n-type /spl beta/-SiC based on electron transport and deformation potential theory

Abstract

The piezoresistive effect in n type /spl beta/-SiC was analyzed on the basis of electron transport and deformation potential theory for cubic many-valley semiconductors. Two deformation potential constants, /spl Xi//sub d/ and /spl Xi//sub u/ of the n-type /spl beta/-SiC, were independently determined by Herring-Vogt theory, which is an extension of Bardeen-Shockley theory for single spherical surface energy semiconductor to the many-valley semiconductor. Shifts of conduction band edges against arbitrary stress components were explicitly formulated by using /spl Xi//sub d/ and /spl Xi//sub u/. Applying stress, the electrons transport between the many-valleys. The electron transport represents macroscopic change in electrical conductivity. Then, shifts of the conduction band edges in each valley were related to the electron transport. Finally, the origin of the piezoresistive effect was interpreted as the electron transport between the many-valleys due to stress. For practical micro mechanical sensor design, piezoresistive coefficients /spl pi//sub 11/ and /spl pi//sub 12/ and gauge factor were calculated as a function of temperature and impurity concentration.