| dc.description.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. | |
