High Breakdown Voltage AlGaN/GaN HEMTs by Employing Proton Implantation

The breakdown voltage of AlGaN/GaN high electron mobility transistors (HEMTs) was increased considerably without sacrificing any other electrical characteristics by proton implantation. The breakdown voltage increased from 416 V of conventional device to 719 V by proton implantation with 150 KeV, 1x10¹⁴cm^-2 fluence after a thermal annealing at 400degC for 5 min under N₂ ambient. The increase of breakdown voltage is attributed to the expansion of depletion region under the 2-dimensional electron gas (2-DEG) channel. The depletion region expanded downwards to the GaN buffer layer because implanted protons act as positive ions and attract the electrons in the 2-DEG channel. Proton implantation successfully reduced the electric field concentration so that the breakdown voltage increased.