Amplification of acoustic waves in piezoelectric semiconductors: Effect of nonlinearity in electron effective mass and collision frequency

Abstract

This paper essentially seeks to provide a theoretical construct to the experimental studies on the acoustoelectric amplification in piezoelectric semiconductors showing that the attenuation of an acoustic wave crosses over to its amplification when electron drift velocity exceeds the acoustic wave velocity. In this paper, first, a phenomenological theory is developed to study the relative change in electron mass and collision frequency when an acoustic wave propagates through piezoelectric semiconductors. Then, analytically, we have shown that this nonlinearity in electron mass and collision frequency arising due to the electric vector of the field associated with the wave can also explain this behavior. Numerical computations are made for a typical case of n-InSb at 77 K.