Berlin 2012 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 69: Quantum Dots and Wires: Transport Properties II (mainly Quantum Dots)

HL 69.3: Vortrag

Mittwoch, 28. März 2012, 17:45–18:00, EW 203

Transient capacitance measurements on GaAs quantum dots — •Jochen Kerbst, Pascal Schoof, Christian Heyn, and Wolfgang Hansen — Institut für Angewandte Physik, Jungiusstr 11, 20355 Hamburg

We investigate the basic physical properties of GaAs quantum dots (QDs) like activation energy for charge carrier emission and capture cross section. For this we embed a layer with QDs in the depletion zone of a Si-doped AlGaAs Schottky barrier and apply Deep Level Transient Spectroscopy (DLTS) [1]. The self assembled GaAs QDs are fabricated in a molecular beam epitaxy (MBE) system by first generating nanoholes in Si-doped AlGaAs utilizing Local Droplet Etching (LDE) [2]. Subsequent filling of the nanoholes with GaAs provides GaAs quantum dots with highly controlled structural properties. This is followed by a further n:AlGaAs layer and a metal gate electrode. For the DLTS measurements we have to separate QD electronic features from deep donors inside the surrounding AlGaAs-matrix. Therefore we have characterized the deep donor levels in AlGaAs as function of the Al concentration.

[1] D.V. Lang, JAP 45, 3023 (1974)

[2] Z. M. Wang, B. L. Liang, K. A. Sablon, G. J. Salamo, Appl. Phys. Lett. 90, 113120 (2007)