A THEORY OF ACOUSTOELECTRIC DOMAINS IN PIEZOELECTRIC SEMICONDUCTORS .I. LINEAR REGIME

White's theory is generalized to include a classical non-electronic loss mechanism and arbitrary time dependence of acoustic wave amplitude. The existence of lattice loss leads to the possibility of overdamped modes with 'phase velocities' which can be in the acoustic range. When νd is close to the unstiffened sound velocity νs or the stiffened sound velocity νp = νs(1 + K2)1/2 non-oscillatory solutions which are a mixture of space-charge and lattice damping are obtained. Those travelling near νp are important in stabilizing the acoustoelectic domain. Lattice loss also raises the threshold field for amplification and if the rate of loss is proportional to ωp the frequency for maximum gain at threshold is lowered below White's value by a factor {(2-p) / (2+p)}1/2.