Comment on "Annealing behavior of a proton irradiated Al/sub x/Ga/sub 1-x/N/GaN high electron mobility transistors grown by MBE"

For original paper see S.J.Cai et al., ibid., vol.47, p.304-307 (2000). The paper by Cai et al. is the first article referring to radiation effects of Al/sub x/Ga/sub 1-x/N/GaN high electron mobility transistors published in this journal. In the paper, authors made use of the shifts of the decomposed three GaN Raman phonon modes E2 to analyze and explain the irradiation effects on GaN. However, we feel that incorrect assignment has been made to the decomposed E2 peaks in GaN and there are obvious errors in citing literature regarding Raman scattering shift rules that warrant comments.