Selective Dynamical Study of Luminescences Near the Surface and the Interface of Epitaxial GaN

Abstract

ABSTRACTRecombination processes and their dynamics are selectively studied (a) near the interface betweeen a 400μm thick GaN epilayer and its Al2O3 substrate and (b) in the structurally relaxed regions near the surface of this sample. Strong radiative excitonic recombination is observed in the relaxed regions. However, the recombination dynamics of free and shallow-bound excitons here are strongly influenced by shallow and deep defects. Near the substrate the presence of dislocations suppresses radiative recombination of free and shallow bound excitons. Deeper emissions appear which we attribute to excitons deeply bound to dislocation-related defects. They exhibit ps-recombination dynamics effected by strong nonradiative contributions.