In this letter, a link between the AlGaN/GaN high-electron-mobility-transistor (HEMT) field plate (FP) and the rate of reoccupation of surface traps is presented. Surface traps are considered to be among the primary factors behind HEMT performance deterioration at high frequencies. Results from simulations using the commercial software package DESSIS are presented, in which the FP is found to reduce trap reoccupation by limiting the tunneling injection of electrons into surface traps in the gate-drain region and thus considerably improve the transient operation of the device.