Transport dynamics of electrons trapped in surface acoustic waves

In this paper, we present a detailed study of electron capture and transport via surface acoustic waves through a semiconductor hetero-structure. The split gate voltage acts as a filter causing rejection of electrons at higher energy states. The filtering process works in theory since, while traveling up the potential barrier, the electrons in each traveling dot will experience the lowering of their effective confining potential. At some point during their upwards journey this confining potential will reach a minimum. Classically we would expect no energies above this minimum to be transmitted and thus the rejection of more energetic electrons. However there are two factors which introduce subtleties into the analysis. Firstly the lowering of the barrier is a time dependent process and the minimum confining potential only lasts a short fraction of time. Secondly we need to take into account quantum mechanical effects such as tunneling through the walls of the dot. Our aim is to understand the underlying mechanics of the transport process and to develop a simple predictive model for the entrapment probabilities. We also analyzed the effects of many experimental parameters, such as the temperature, frequency, velocity and amplitude of the surface acoustic wave, as well as the characteristics of the semiconductor hetero-structure, on the electron transport dynamics.