Reduced nonradiative recombination rates in c-plane Al0.83In0.17N films grown on a nearly lattice-matched GaN substrate by metalorganic vapor phase epitaxy

Abstract

A record-long room-temperature photoluminescence (PL) lifetime (τPLRT) of approximately 70 ps was obtained for the sub-bandgap 3.7 eV emission band of a 300-nm-thick c-plane Al0.83In0.17N epilayer for the use in cladding layers of an edge laser structure, which were grown by metalorganic vapor phase epitaxy on a low threading dislocation density nearly lattice-matched GaN substrate. The recorded τPLRT value was twice as long as previously reported ones, indicating half concentration of nonradiative recombination centers. Room-temperature spatially resolved cathodoluminescence intensity images for the 3.7 eV band revealed nearly zero carrier diffusion length, which is consistent with the fact that τPLRT of 70 ps is 1/35 of the near-band-edge emission of the GaN substrate (2.4 ns). As the PL decay curves for the 3.7 eV band were sufficiently fitted by the stretched exponential function, the emission likely originates from extended states such as impurities, point defects, and their complexes, as well as localized states of uneven potential profile.