Correlación de la emisión de luz y características de difracción de rayos X en pozos cuánticos con puntos cuánticos embebidos

Abstract

This thesis presents the photoluminescence (PL) study of a group of five wafers of InAs quantum dots (QDs) embebed in an InxGa1-xAs quantum well (QWs) with an In concentration about 0.15. These wafers has different quantum dot density from the range 1.1x10 11 – 1.3x1010cm-2 obtained by the QD growth temperature variation in the range 470°C – 535°C. The photoluminescence study revealed a non monotonous change in the (PL) peak positions and in the (PL) integrated intensities. The peak position analysis has been done using the Varshni and Einstein formulas. From this analysis we concluded that the process of Ga-In interdiffusion has realized at the InGaAs/InAs QD interface. The Ga-In interdiffusion process has a non monotonous behavior versus temperature too. The last effect can be explained as a result of the different elastic stress levels in the wafers. An X-ray diffraction (XRD) study has been done in order to determine the elastic stress in the structures. The XRD study showed that the diffraction peaks of the GaAs and InGaAs QW (400) planes has a non monotonous shift relatively the XRD peak from the (400) planes of the cubic GaAs and InGaAs. The X ray diffraction study revealed that in the wafers #2, #3 and #4 the elastic deformation (or elastic stress) are minimum in comparation with those levels in wafers #1 and #5. The high values in elastic stress in wafers #1 and #5 enhance i) the decrease of InAs QDs PL intensity ii) the efficient Ga-In interdiffusion at the InGaAs/InAs QDs interface and iii) the shift of the QDs PL peaks to high energy.