Photoluminescence study on coarsening of self-assembled InAlAs quantum dots on GaAs (001)

Red-emission at similar to 640 nm from self-assembled In0.55Al0.45As/Al0.5G a0.5As quantum dots grown on GaAs substrate by molecular beam epitaxy (MBE) has been demonstrated. We obtained a double-peak structure of photolumines cence (PL) spectra from quantum dots. An atomic force micrograph (AFM) imag e for uncapped sample also shows a bimodal distribution of dot sizes. From the temperature and excitation intensity dependence of PL spectra, we found that the double-peak structure of PL spectra from quantum dots was strongl y correlated to the two predominant quantum dot families. Taking into accou nt quantum-size effect on the peak energy, we propose that the high (low) e nergy peak results from a smaller (larger) dot family, and this result is i dentical with the statistical distribution of dot lateral size from the AFM image.