Ion beam studies of InAs/GaAs self assembled quantum dots

In this study we combine Rutherford backscattering/channelling (RBS-C) and high resolution X-ray diffraction (HRXRD) to study the structural properties of the InAs/GaAs structures. The InAs/GaAs QD heterostructures were grown by atmospheric pressure metal organic vapour phase epitaxy. Channelling measurements reveal a good crystalline quality along the main axial directions with minimum yields in the range of 4-6% through the entire capping layer. An increase on the dechannelling rate was observed in the region where the InAs quantum dots were buried. The channelling results also give evidence for the presence of defects preferentially oriented. Detailed angular scans in a structure with a 28 nm cap allowed the study of the In orientation with respect to the GaAs matrix and a perfect alignment was found along the growth direction. The strain in the dots shifts the angular curves along the tilt directions.