Growth and doping of bulk GaN by hydride vapor phase epitaxy
Zhang Yu-Min1, 2, Wang Jian-Feng1, 2, †, Cai De-Min2, Ren Guo-Qiang1, Xu Yu1, 2, Wang Ming-Yue1, 2, Hu Xiao-Jian1, 2, Xu Ke1, 2, ‡
       

(a) The room-temperature photoluminescence spectra of GaN samples sliced from the bulk GaN crystal. The inset is the amplified YL band of each sample, which is normalized according to the NBE intensity. (b) The relationship between Si concentration and dislocation density at room temperature. (c) The relationship between IYL/IBE and dislocation density at room temperature.[82]