Numerical model for electrical charge injection in the acoustic charge-transport device

A two dimensional model is developed to study the electrical charge injection process at the input of a GaAs buried-channel acoustic charge-transport device. The model allows for nonuniform impurity doping profiles, variable epitaxial layer configurations, and arbitrary structural designs of the input electrode architecture. The acoustic wave potential is incorporated as a time- and space-varying doping density that adds directly to the impurity doping density. The wave-induced doping density is obtained from the piezoelectric displacement charge that accompanies the acoustic wave. The partial differential equations which form the mathematical basis of the charge injection process are derived from the semiconductor transport equations and solved numerically. The algorithm for simulating charge injection and the results of a simulation are presented. This model provides a means for characterizing the electrical performance of the acoustic charge-transport device input circuit in terms of device physics