Improved analytical model for threshold behavior of sidegating effect in GaAs metal–semiconductor field-effect transistors induced by impact ionization of deep traps

This article presents an improved analytical model for the threshold behavior of the sidegating effect in GaAs metal-semiconductor field-effect transistors. The model takes into account impact ionization of deep trap EL2 and the charge neutrality condition in the undoped semi-insulating GaAs substrate. Based on the model, we provide a new simple analytical expression for the threshold voltage of the sidegating effect (V_th). The new expression of V_th indicates that V_th is proportional to not only the distance of sidegate from the channel but to the substrate impurity compensation ratio ξ also. The model predicts that closely compensated substrates will minimize the sidegating effect in agreement with earlier experimental results. © 1999 American Institute of Physics.