Emission and HR-XRD study in InAs quantum dot structures prepared at different QD's growth temperatures

The structure of the symmetric GaAs/In0.15 Ga0.85GaAs/GaAs quantum wells (QWs) with embedded InAs quantum dots (QDs) has been studied using High resolution X-ray diffraction HR-XRD method. The QDs were grown at different temperatures from the range 470 - 535°C. The increase of growth temperature stimulates decreasing the QD surface density and the enlargement of QD lateral sizes. Simultaneously, the variation of PL intensity and PL peak position non monotonously have been detected. To understand the reason of PL variations the HR-XRD method with a resolution of 0.0001 degree has been applied. The high intensity peaks that correspond to the diffraction from the (400) crystal planes in GaAs QWs, InAs QDs and InxGa1-xAs QWs have been detected by HR-XRD. The simulation fitting of experimental HR XRD curves has been done on the base of the dynamic diffraction theory. This simulation fitting testifies the different level of intermixing of Ga/In atoms in QDs and QW layers in studied QD structures. The simulation fitting parameters for QD structures with the QDs grown at 490°C and 510°C are very close to the original technological parameters. The simulation fitting parameters in QD structures with QDs grown at the temperatures 470°C, 525°C and 535°C are very different from technological one. Actually in these QD structures the process of Ga/In intermixing is essential due to the higher level of elastic strains that stimulates the variation of PL parameters as well.