Regensburg 2002 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 11: Poster 1

HL 11.64: Poster

Montag, 11. März 2002, 17:00–19:30, Poster A

PL investigation of isolated InAs quantum dots on GaAs vicinal surfaces — •V. G. Talalaev¹, B. V. Novikov¹, V. V. Katchkanov¹, A. V. Efremov¹, R. Goldhahn², and G. Gobsch² — ¹Institute of Physics, St. Petersburg State University — ²Institut für Physik, Technische Universität Ilmenau

In metastable arrays of quantum dots (QDs) their 0D properties are more prominent than for stable QDs. Furthermore, in case of QD arrays on vicinal substrates their size is reduced, and their uniformity and surface density are increased. In both cases there is a narrowing and intensification of the photoluminescence (PL) band. We have investigated the PL of 2D arrays of metastable InAs QDs obtained by submonolayer migration enhanced epitaxy on vicinal GaAs substrates with misorientation angles of 0-7^o. The PL spectrum has a multimodal structure which is explained by the existence of two QD groups having basically different origins. On the one hand, physically isolated QDs (IQDs) are formed on vicinal substrates with a high misorientation degree. Their formation is attributed to the isolation of separate InAs clusters on vicinal terraces due to the wetting layer rupture at the edges of bunched multiatomic steps. The carrier exchange between IQDs is strongly limited. The absence of collective QD properties provides good conditions for studying intrinsic properties of single QDs. On the other hand, a second type of metastable QDs forms chains resulting in path-shaped conjunct QDs (CQDs). It has been shown that the CQD PL is mostly caused by transitions involving excited states. Tunneling processes play the main role during the excitation relaxation inside the CQD group.