Processing and characterization of a free-standing bulk polycrystalline GaN layer

Vacancy-modified few-layered GaN crystal for novel high-temperature energy storage

“…2b shows that the characteristic E 2 (high) peaks of the bulk GaN crystal (566.7 cm −1 ) and GaN-2.5 h crystal (566.0 cm −1 ) correspond well with the previous report. 19 In addition to the E 2 (high) phonon vibration modes, the A 1 (TO) phonon vibration mode with a peak at 529.3 cm −1 and the E 1 (TO) phonon vibration mode with a peak at 558.8 cm −1 are observed, because of the exposure of more defects on the different GaN-2.5 h crystal surfaces. 20 According to previous reports, the vibration modes of 417.2 cm −1 and 657 cm −1 are caused by vacancies inside the lattice and defect level occurring in the conduction band minimum (CBM) of the GaN crystal.…”