Effect of the InAlGaP matrix on the growth of self-assembled InP quantum dots by metalorganic chemical vapor deposition

Abstract

InP self-assembled quantum dots (QDs) were deposited on lattice-matched In0.5(AlxGa1−x)0.5P matrices grown on (001) GaAs substrates by using metalorganic chemical vapor deposition. We found that the Al concentration in the matrix has a great influence on the size of the InP QDs. For a fixed volume of deposited InP, the size of the QDs decreases with an increase in the Al concentration in the In0.5(AlxGa1−x)0.5P matrix. We suggest that this variation in QD size is a result of an alloying effect caused by atomic intermixing between the InP dots and the underlying matrix material. The stronger intermixing between InP and the Ga-rich matrices (relative to Al-rich matrices) results in larger QDs on these surfaces. The intermixing effect, as expected, reduces the lattice mismatch and, as a result, leads to a larger critical thickness of the wetting layer when the growth temperature is higher. The growth of InP QDs on an InAlP matrix with a thin GaP intermediate buffer layer also supports the interpretation as an intermixing effect.