We present a theoretical study on the electric field driven plasmon dispersion of the two-dimensional electron gas （2DEG） in A1GaN/GaN high electron mobility transistors （HEMTs）. By introducing a drifted Fermi-Dirac distribution, we calculate the transport properties of the 2DEG in the A1GaN/GaN interface by employing the balance-equation approach based on the Boltzmann equation. Then, the nonequilibrium Fermi-Dirac function is obtained by applying the calculated electron drift velocity and electron temperature. Under random phase approximation （RPA）, the electric field driven plas- mon dispersion is investigated. The calculated results indicate that the plasmon frequency is dominated by both the electric field E and the angle between wavevector q and electric field E. Importantly, the plasmon frequency could be tuned by the applied source-drain bias voltage besides the gate voltage （change of the electron density）.
