Red luminescence from freestanding GaN grown on LiAlO2 substrate by hydride vapor phase epitaxy

Photoluminescence (PL) spectroscopy was used to study the red luminescence band from freestanding GaN grown on LiAlO2 substrate by hydride vapor phase epitaxy. The red luminescence band was observed with its peak at 1.78 eV and 1.85 eV at 10 K and 300 K, respectively. Temperature‐dependent PL data show that the 1.78 eV red band is due to a donor‐acceptor pair (DAP) transition. Excitation‐intensity‐dependent PL measurements at 10 K and 300 K reveal that the 1.85 eV band at 300 K is the overlap of the DAP band and the electron‐to‐acceptor (e, A0) transition band. Ion‐implantation experiments confirmed that both carbon and oxygen impurities are involved in the red luminescence transition. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)