Schedule 0 4:15 PM - 4:30 PM [LEDIA4-03] Correlation between Etch Pit Size and Threading Dislocation Propagation Habit in GaN Substrate Observed by Multiphoton-Excitation Photoluminescence *Mayuko Tsukakoshi1, Tomoyuki Tanikawa1, Masahiro Uemukai1, Ryuji Katayama1 (1. Osaka University)