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HL: Fachverband Halbleiterphysik

HL 89: Optical Properties II

HL 89.4: Vortrag

Freitag, 18. März 2011, 11:00–11:15, POT 251

Air-Gap Heterostructures — •Jochen Kerbst, Matthias Schmidt, Stephan Schwaiger, Andrea Stemmann, Stefan Mendach, Wolfgang Hansen, and Christian Heyn — Institut für Angewandte Physik, Jungiusstr 11, 20355 Hamburg

We demonstrate the fabrication of a novel type of heterostructure providing epitaxial semiconductor layers which are separated by thin air gaps. The air gaps with thickness ranging from 4 to 8 nm are stabilized by low-density nanopillars. The nanopillars are generated by a combination of self-assembled droplet etching (LDE) [1,2] during molecular beam epitaxy (MBE) and post-growth selective etching. In particular, first a thin AlAs layer is grown on a GaAs substrate. Afterwards, local etching with Ga droplets forms nanoholes deeper than the thickness of the AlAs layer. The nanoholes are filled with GaAs and finally overgrown with a 50 or 100 nm thick GaAs film. After removal of the samples from the MBE system, wet chemical selective etching of only the AlAs layers yields the formation of the air-gab heterostructures. The thickness of the air gaps is precisely controlled by the thickness of the initial AlAs layers. Reflectivity measurements confirm the existence of the air gaps and the gap thickness.

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

[2] Ch. Heyn, A. Stemmann, and W. Hansen, Appl. Phys. Lett. 95, 173110 (2009)