Theoretical Model and Experimental Study of Effects of Rapid Thermal Annealing on Self-assembled In(Ga)As/GaAs Quantum Dots

This paper presents a study of rapid thermal annealing (RTA) effects on self-assembled In(Ga)As/GaAs quantum dots (QDs) using Raman scattering and photoluminescence (PL) spectroscopy. The PL dependence on excitation shows the existence of two size distributions of QDs (small and large) after annealing. However, Raman scattering shows one longitudinal optical (LO) phonon peak of the QD. We have presented two simple models (Raman scattering model (RSM) and PL model) to determine both composition and size of QDs. First, in the RSM, we have taken into account the strain effects. Second, in the PL model, we have assumed a conical QD shape, and we have taken into account the electron-hole confinement, strain effect, and the electron-hole Coulombic interaction. A Gaussian distribution has been introduced to describe the random distribution of indium content for different QDs. We initiated our study with the simulation of the Raman spectra by the RSM to determine the value of indium content of InxGa1-xAs QDs before and after annealing. We have introduced this value into the PL model to determine the QD size. Finally, we found a weak FWHM of composition distribution that shows a homogeneous indium composition in different QDs in both as-grown and annealed QDs.