Increase of Breakdown Voltage on AlGaN/GaN HEMTs by Employing Proton Implantation

The breakdown voltage of new AlGaN/GaN high electron mobility transistors (HEMTs) was increased considerably without sacrificing any other electrical characteristics by proton implantation. The breakdown voltage of proton-implanted AlGaN/GaN HEMTs with 150 KeV 1 times 10
¹⁴
-cm
^-2
fluence after thermal annealing at 400 degC for 5 min under N
₂
ambient was 719 V, while that of conventional device was 416 V. The increase of the breakdown voltage is attributed to the expansion of the depletion region under the 2-D electron gas (2-DEG) channel. The depletion region expanded downward into the GaN buffer layer because implanted protons acted as positive ions and attracted electrons in the 2-DEG channel.