Molecular Beam Epitaxial Growth and Characterization of the Vertically Aligned InAs Quantum Dots Embedded in Al_<0.5>Ga_<0.5>As

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In this paper we describe structural and optical properties of vertically aligned InAs quantum dots(QDs)embedded in Al_<0.5>Ga_<0.5>As.These aligned QDs were grown at 520℃ in the Stranski-Krastanow growth mode of molecular beam epitaxy.Measurements by reflection high-energy electron diffraction and atomic force microscopy showed that both the size and density of these QDs increased with the number of stacking periods.The temperature dependence of the wavelength-integrated photoluminescence(PL)intensity revealed that the intense emission from excitons, which dominated the PL spectra at low temperatures, was easily thermally quenched by the large dots in the upper layers.To improve these unfavorable characteristics, we employed a size- and density-controlled growth procedure for the QDs in the upper layers, and succeeded in increasing the PL stability at high temperatures.We also studied a postgrowth annealing treatment for these aligned QD-structures, and found that it is effective to increase the PL intensity when the annealing is performed at around 570℃.By combining the controlled growth procedure with the postgrowth annealing treatment, we realized a strong excitonic emission of which the quenching temperature associated with an activation energy of 0.65eV was as high as ∿300K.
社団法人応用物理学会の論文
2000-04-15