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HL: Fachverband Halbleiterphysik

HL 8: Interfaces/ surfaces

HL 8.1: Vortrag

Montag, 25. Februar 2008, 14:00–14:15, EW 201

Influence of group-V exchange processes and Sb segregation on the interface quality of GaSb/GaAs quantum wells — •Rainer Timm¹, Andrea Lenz¹, Lena Ivanova¹, Holger Eisele¹, Ian Farrer², David A. Ritchie², Ganesh Balakrishnan³, Diana L. Huffaker³, and Mario Dähne¹ — ¹Institut für Festkörperphysik, Technische Universität Berlin, Deutschland — ²Cavendish Laboratory, University of Cambridge, UK — ³Center for High Technology Materials, University of New Mexico, Albuquerque, USA

GaSb nanostructures in GaAs show a staggered type-II band alignment with a large hole confinement, making them very promising for optoelectronic and charge storage device applications. For such devices, however, the correct chemical composition of the nanostructures and the abruptness of their interfaces are both crucial and challenging [1]: While intermixing at the GaSb-on-GaAs interface can partly be controlled using an Sb soaking step, atomic exchange processes leading to strong Sb segregation upon GaAs overgrowth of a GaSb layer are even more difficult to avoid.

Using cross-sectional scanning tunneling microscopy [2], we were able to study the interfaces of various MBE-grown GaSb/GaAs quantum wells at the atomic level, including the wetting layers between quantum dots. By systematically varying the growth conditions, the influences of Sb soaking, intermixing effects, As-for-Sb exchange upon GaAs overgrowth, and Sb acting as surfactant could be distinguished.

[1] I. Farrer et al., J. Crystal Growth 251, 771 (2003).

[2] R. Timm et al., Appl. Phys. Lett. 85, 5890 (2004).