Carrier relaxation and recombination in an InGaN/GaN quantum well probed with time-resolved cathodoluminescence

Abstract
Spatially, spectrally, and temporally resolved cathodoluminescence (CL) techniques have been employed to examine the optical properties and kinetics of carrier relaxation for metalorganic chemical vapor deposition grown InGaN/GaN single quantum wells (QWs). Cathodoluminescence wavelength imaging of the QW sample revealed local band gap variations, indicating the presence of local In composition fluctuations and segregation during growth. A detailed time-resolved CL study shows that carriers generated in the boundary regions will diffuse toward and recombine at InN-rich centers, resulting in a strong lateral excitonic localization prior to radiative recombination.