Direct measurement of quantum levels in InAs/GaAs QDs by BEEM / BEES

0377299 - FZÚ 2013 RIV SK eng C - Conference Paper (international conference)
Hulicius, Eduard - Vaniš, Jan - Pangrác, Jiří - Walachová, Jarmila - Vyskočil, Jan - Oswald, Jiří - Hospodková, Alice
Direct measurement of quantum levels in InAs/GaAs QDs by BEEM / BEES.
17th Conference of Czech and Slovak Physicists Proceedings. Košice: Slovak Physical Society, 2012 - (Reiffers, M.), s. 105-107. ISBN 978-80-970625-4-5.
[Conference of Czech and Slovak Physicists/17./. Žilina (SK), 05.09.2011-08.09.2011]
R&D Projects: GA ČR GAP102/10/1201; GA ČR GA202/09/0676
Institutional research plan: CEZ:AV0Z10100521; CEZ:AV0Z20670512
Keywords : quantum dots * InAs * GaAs * MOVPE * BEEM * BEES
Subject RIV: BM - Solid Matter Physics ; Magnetism

Structures with self assembled quantum dots were prepared by low pressure MOVPE using Stranski-Krastanow growth mode. One single layer of InAs QDs confined between thin GaAs layers was embedded in ternary AlGaAs material. GaAs buffer and capping layers were also used. QDs were detected by ballistic electron emission microscopy BEEM. Ballistic current IB through QDs is much higher than outside of QDs, and QDs look like dark spots. Ballistic electron emission microscopy BEES characteristics IB-V were measured on individual QDs. Derivation dIB/dV corresponds to the density of states. Minima in the density of states are assigned to the positions of the quantum levels in the QD. The spectroscopic characteristics of individual QDs were examined. One-electron p1-like state, one- and two-electron ground states and excited two-electron states were found. The Coulomb interaction and exchange energies between two electrons in QDs were also determined.
Permanent Link: http://hdl.handle.net/11104/0209496