Acceptors responsible for the 2.2, 2.9 and 3.27 eV photoluminescence (PL) bands in undoped GaN were studied by transient PL. A non-exponential decay of PL intensity for all the three bands is observed at low temperature consistent with donor-acceptor pair recombination. The transitions are attributed to recombination involving a shallow donor and three different acceptors. At temperatures in excess of about 100 K a new recombination process emerges as evident from the nearly exponential PL decay. We attribute this to free-to-bound transitions involving free electrons and acceptors. Electron-capture cross-sections of 3 × 10-19, 2 × 10-20 and 3 × 10-21 cm2 are calculated for the acceptors responsible for the 3.27, 2.9 and 2.2 eV bands. These acceptors are attributed to multiply charged defects involving a gallium vacancy.
- Transient photoluminescence
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering