Berlin 2008 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 44: Quantum dots and wires: preparation and characterization II

HL 44.5: Vortrag

Donnerstag, 28. Februar 2008, 17:45–18:00, EW 201

Dependence of InGaN quantum dot formation on two-step growth parameters — •Christian Tessarek, Stephan Figge, Detlef Hommel, Joachim Kalden, Kathrin Sebald, and Jürgen Gutowski — Institut für Festkörperphysik, Universität Bremen, Otto-Hahn-Allee 1, 28359 Bremen

InGaN is a potential candidate for the application in LED and lasers with emission in the blue-green spectral region. Compared to quantum wells (QWs) it is expected to have an improvement in the optical and electrical characteristics of a device by implementing InGaN quantum dots (QDs).
The overgrowth of Stranski-Krastanov-type QDs with a GaN-capping layer leads to the dissolution of the QD structures. Utilizing a two-step-growth-mode we succeeded to grow capped QDs. The first step in this growth is the deposition of a few monolayer thin In_xGa_1−xN nucleation layer (NL) which is stabilized in a second step by growing a In_yGa_1−yN formation layer (FL) with y<x. The resulting structure shows both QW as well as QD related luminescence as we proved by micro-photoluminescence (PL) measurements. To achieve sole QD luminescence the QW contribution has to be suppressed while not dissolving the QDs. For this reason we have investigated the effect of different gas fluxes during the growth of NL and FL on the QD and QW PL. Furthermore, we will present the impact of growth interruptions and growth temperatures on the PL-spectra. Finally, the growth on different AlGaN templates and the influence of strain is investigated.