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 behavi or of the sidegating effect in GaAs metal-semiconductor field-effect transi stors. The model takes into account impact ionization of deep trap EL2 and the charge neutrality condition in the undoped semi-insulating GaAs substra te. Based on the model, we provide a new simple analytical expression for t he 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 sideg ate from the channel but to the substrate impurity compensation ratio xi al so. The model predicts that closely compensated substrates will minimize th e sidegating effect in agreement with earlier experimental results. (C) 199 9 American Institute of Physics. [S0021-8979(99)07401-0].