Power Flow and Energy Storage in Piezoelectric Semiconductor Devices

Traditionally the phenomenological constitutive relations for piezoelectric materials explicitly relate the electric displacement D¯ the electric intensity E¯, the stress tensor, and the strain tensor. This paper presents a new formulation for the theory of coupled wave interactions in a class of important hexagonal piezoelectric devices; here an equivalent dielectric description explicitly involving only D¯ and E¯ replaces (without approximation) the traditional formulation. The new formulation supplies the foundation for a new determination of power flow and energy storage on a basis broad enough to include the effects of diffusion and collisions on multivelocity multispecies carrier streams. The results, when specialized to a single-velocity single-species carrier stream, differ significantly with others recently proposed for those circumstances. The general results display a considerable degree of compactness and simplicity and are "electrically invariant" in that they hold for insulating, photoconducting, and semiconducting piezoelectric materials without any change in basic form.