Regensburg 2013 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 41: Quantum dots and wires: Preparation and characterization

HL 41.6: Talk

Tuesday, March 12, 2013, 12:30–12:45, H15

Confinement enhancement in InGaN quantum dots by AlGaN barriers — •Carsten Laurus, Timo Aschenbrenner, Stephan Figge, Marco Schowalter, Andreas Rosenauer, and Detlef Hommel — Institute of Solid State Physics, University of Bremen, Otto-Hahn-Allee, 28359 Bremen, Germany

InGaN quantum dots (QDs) are of great interest to realize single photon emitters for quantumcryptography. Single photon emission (SPE) up to 50 K was achieved utilizing spinodal phase decomposition for QD formation [S.Kremling, APL 100, 061115 (2012)]. One approach reaching SPE at 300 K is the implementation of a barrier which improves the confinement of charge carriers and thus the temperature stability. Using InGaN as active layer, AlGaN is a promising barrier material because of its higher bandgap. Several sample series were grown by MOVPE with respect to diverse growth parameters e.g. growth temperature of the AlGaN barrier, barrier thickness and aluminum concentration of the barrier. For structural analysis by SEM samples without a GaN capping layer were used, whereby µ-PL investigations were made with capped samples. Based on SEM data the surface structures of the uncapped samples are divided in two phases with different indium concentration. The indium-rich phase consists mostly of islands and the indium-low is a meander-like structure which are QDs. On the basis of TEM data the quality of the AlGaN barrier in dependence of the aluminum concentration will be evaluated. Furthermore the capping of InGaN QDs with GaN or AlGaN and its problems will be discussed.