Transient photoluminescence of defects in undoped GaN prepared by metal organic vapor phase epitaxy

Transient behavior of the 2.3, 2.9 and 3.27 eV photoluminescence (PL) bands in undoped GaN is studied. A nonexponential decay of PL intensity is obser ved for all three bands after pulsed excitation at low temperature. Transit ion rates were measured for the three bands. Quantitative analysis of the P L decay indicates that all three bands are associated with donor acceptor p air (DAP) transitions involving a shallow donor and three acceptor states o f different origins. The transition rate decreases with decreasing band ene rgy or increasing thermal ionization energy of the acceptor. (C) 1999 Elsev ier Science B.V. All rights reserved.