Variación y no homogeneidad de la fotoluminiscencia en puntos cuánticos de InAs embebidos en pozos cuánticos de InGaAs

Abstract

The samples of InAs quantum dots embedded in InGaAs/GaAs QWs were created at different temperatures of QD growth from the range of 470ºC up to 535ºC by selfassembled Stransky-Krashtanov growth mode using the MBE technique. The photoluminescence dependence on temperature and excitation power of measurements and the non homogeneity of photoluminescence along the wafers in QD structures have been studded. The PL non homogeneity is characterized by 2 reasons: i) the PL intensity variation without the change of PL peak positions in structures with QDs obtained at 470 and 490 C is related to the variation of QD or nonradiative center concentrations along the wafer, and ii) the PL intensity variation with the change of PL peak positions in structures with QD obtained at 510, 525 and 535 oC is related to the variation of QD sizes along the wafer, This effect is due to more deep localized energy levels in QD in the center of wafer in comparison with the energy levels in QD at the periphery. The study of PL intensity variation in QD obtained at 470, 490, 510, 525 and 535oC has shown that 3 reasons exist: a) the high concentration of nonradiative recombination centers in capping layer In0.15Ga1-0.15As for QD obtained at low temperature of 470oC, b) the dispersion of the density and the size of QD obtained at 490, 510 and 525oC, c) the high concentration of nonradiative recombination centers in the barrier layer GaAs for QD obtained at 535oC.