Growth of InP self-assembled quantum dots on strained and strain-relaxed Inx(Al0.6Ga0.4)1−xP matrices by metal-organic chemical vapor deposition

Abstract

InP self-assembled quantum dots (QDs) were deposited on Inx(Al0.6Ga0.4)1−xP matrices grown on GaAs (001) substrates by metal-organic chemical vapor deposition. By adjusting the indium concentration in the Inx(Al0.6Ga0.4)1−xP matrices, the effects of strain and its relaxation in the matrix on the cathodoluminescence (CL) properties and morphology of grown QDs were studied. We found that the CL intensity of the InP QDs increases with an increase in the indium composition in the Inx(Al0.6Ga0.4)1−xP matrix. For QDs grown on strain-relaxed matrices, CL imaging studies show that the CL of QDs close to dislocation lines in tensile-strained Inx(Al0.6Ga0.4)1−xP matrices is much weaker than in the surrounding strained areas, while in the compressively strained matrices, the CL of the QDs close to dislocations is much brighter. The morphology of uncapped QD samples shows that QDs on top of (or close to) dislocations are not well developed in the tensile matrices but are much larger and have a higher density in compressively strained matrices as compared to the surrounding strained areas. Details of the strain effect on the CL properties and on the nucleation of QDs are discussed.