Low-Frequency Noise Characteristics in Ion-Implanted GaN-Based HEMTs

Low-frequency noise characteristics in ion-implanted GaN/AlGaN/GaN and AlGaN/GaN HEMTs were investigated. The normalized spectral noise density was about 6 dB lower in GaN/AlGaN/GaN HEMTs than in AlGaN/GaN HEMTs. The normalized spectral noise density dependence on the gate length Lg indicates that the main origin of low-frequency noise is at the region under the gate in both devices. The Hooge parameters alphaH for both devices are on the order of 10^-1-10^{- 2}. The ion implantation process introduces a lot of defects in the source/drain regions, but the values of alphaH are comparable with those for conventional GaN-based HEMT devices. The values of alphaH are also lower in GaN/AlGaN/GaN HEMTs than in AlGaN/GaN HEMTs, which is due to the decrease of surface potential fluctuations in GaN/AlGaN/GaN HEMTs.