Regensburg 2010 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 13: Quantum Dots and Wires: Preparation and Characterization I
HL 13.3: Vortrag
Montag, 22. März 2010, 14:30–14:45, H17
Improvement of the optical quality of site-controlled InAs quantum dots by a double stack growth technique in wet-chemically etched holes — •Tino Johannes Pfau1, Aleksander Gushterov1, Johann-Peter Reithmaier1, Isabelle Cestier2, Gadi Eisenstein2, Evgany Linder3, and David Gershoni3 — 1Technische Physik, INA, Universität Kassel, 34132 Kassel — 2Electrical Engineering Dep., Technion, Haifa 32000, Israel — 3Solid State Institute and Physics Dep., Technion, Haifa 32000, Israel
The optimization of the wet-chemically etching of holes and a special MBE growth stack technique allows enlarging the site-control of low density InAs QDs on GaAs substrates up to a buffer layer thickness of 55 nm [1]. The strain of InAs QDs, grown in the etched holes, reduces the hole closing, so that a pre-patterned surface is conserved for the second QD layer. The distance of 50 nm GaAs between the two QD layers exceeds drastically the maximum vertical alignment based on pure strain coupling (20 nm). Compared to stacks with several QD layers, this method avoids electronic coupling between the different QD layers and reduces the problems to distinguish the dots of different layers optically.
Confocal microphotoluminecence reveals a significant diminution of the low temperature photoluminescence linewidth of the second InAs QD layer to an average value of 505 ± 53 µ eV and a minimum width of 460 µ eV compared to 2 to 4 meV for QDs grown on thin buffer layers. The increase of the buffer layer thickness decreases the influence of the surface defects caused by prepatterning.
T. J. Pfau, et al., Appl. Phys. Lett. 95 (2009)