Optical phonons as a probe to determine both composition and strain in InxAl(1-x)As quantum dots embedded in an AlAs matrix
Résumé
InxAl(1-x)As quantum dots (QDs) embedded in an AlAs matrix were studied using Raman scattering and photoluminescence spectroscopy techniques. The longitudinal optical (LO) and transverse optical (TO) In-As bond vibrations frequencies are found to depend on both composition and strain. Using different scattering geometries (allowed for LO or for TO modes) we were able to obtain the experimental values of these frequencies. By comparing these values with the calculated frequencies, one can determine both the mean composition (stoichiometry parameter x) and the biaxial strain in InxAl(1-x)As QDs embedded in an AlAs matrix. Our approach is simple, non-destructive and fast.