In order to alleviate the negative impacts of high temperature (850 degrees C) annealing on high electron mobility transistor (HEMT) technology, a process required only low temperature annealing (less than 600 degrees C) was introduced to form ohmic contact to HEMT. By the process, the electrode was in contact with the AlGaN/GaN interface. The value of specific contact resistivity (rho(c)) of the ohmic contact was 6.29 x 10(-5) Omega cm(2). An improved HEMT power device was presented. For comparison, a conventional device with Ti/Al/Ni/Au ohmic contact annealed at 850 degrees C was prepared. It was found that after annealing at 600 degrees C, the sheet resistance (Rsh) of the improved device decreased to 313 Omega/square (74.5% of that of the conventional device), and the advantage of our process on device performance was greater as the distance between ohmic contacts increased. The saturation current of the improved device was increased by approximately 23% when the distance between source and drain was 40 mu m.