A new annealing method employing excimer laser pulses is proposed to improve the transfer characteristics and the breakdown voltage of the AlGaN/GaN high electron mobility transistor (HEMT). The XeCl excimer laser pulses annealed the unpassivated AlGaN/GaN HEMT after the Schottky gate metallization. The interface defects between the Schottky gate metal and the GaN layer decreased due to the lateral heat diffusion of the laser pulses. The experimental results show that the drain current and the peak extrinsic transconductance of the AlGaN/GaN HEMT after laser pulses annealing were 496 mA/mm and 134 mS/mm while a virgin device exhibited 434 mA/mm and 113 mS/mm, respectively. (c) 2005 The Electrochemical Society.