Indirect and direct optical transitions in In_(0.5)Ga_(0.5)As/GaP quantum dots

摘要

We present a study of self-assembled In_(0.5)Ga_(0.5)As quantum dots on GaP(001) surfaces linking growth parameters with structural, optical, and electronic properties. Quantum dot densities from 5.0 × 10~7 cm~(-2) to 1.5 × 10~(11) cm~(-2) are achieved. A ripening process during a growth interruption after Ino.5Gao.5As deposition is used to vary the quantum dot size. The main focus of this work lies on the nature of optical transitions which can be switched from low-efficient indirect to high-efficient direct ones through improved strain relief of the quantum dots by different cap layers.