Study of self-organized InAs/GaAs quantum dots by photoluminescence and photoreflectance

By using photoluminescence and photoreflectance ranging from 8 to 300K, this study investigates transition energies in InAs/GaAs quantum dot (QD) samples grown on (100) misoriented 7^o towards (110) GaAs substrates using gas source molecular beam epitaxy with various V/III ratios. Only exciton transition appears in the PL spectra of all samples. Experimental results indicate that the decrease of the FWHM of the PL peak with an increasing temperature can be attributed to the effective suppression of non-predominant size QD emissions due to carrier tunneling between nearby dots. Signals from all relevant portions of the samples have been observed in the PR spectra. One to three transition energies in QDs, depending on the dot size, are observed in the PR spectra. Furthermore, the binding energies of excitons and thus the QD size are estimated from the temperature dependence of the exciton energies and the first transition energies of QDs.