Carrier recombination at single dislocations in GaN measured by cathodoluminescence in a transmission electron microscope

We study radiative and nonradiative recombination at individual dislocations in GaN by cathodoluminescence performed in a transmission electron microscope. The dislocations are produced by indentation of dislocation free single crystals and have a-type Burgers vectors (b=1/3[11 (2) over bar0]). They are aligned along [11 (2) over bar0] directions in the basal plane. Our direct correlation between structural and optical properties on a microscopic scale yields two main results: (i) 60degrees-basal plane dislocations show radiative recombination at 2.9 eV; (ii) screw-type basal plane dislocations act as nonradiative recombination centers. We explain the nonradiative recombination by splitting this dislocation into 30degrees partials that have dangling bonds in the core. The dissociation width of these dislocations is <2 nm. (C) 2002 American Institute of Physics.