Prepassivated AlGaN/GaN HEMTs with improved edge acuity in annealed ohmic contacts

Sharp edge definition of annealed ohmic contacts is of great concern in AlGaN/GaN high electron mobility transistors (HEMTs) because it is strongly associated with breakdown voltage uniformity and reliability. In this reported work, two-step sequential annealing in conjunction with a low-damage SiN_x dry etching technique was employed in a prepassivation process in order to improve the edge acuity in annealed ohmic contacts. As a result, uniformity in breakdown voltage was significantly improved in comparison with a conventional process.