X-Ray Diffraction Analysis of Lateral Composition Modulation in InAs/GaSb Superlattices Intended for Infrared Detector Applications

Lateral compositional modulation in a (InAs)13/(GaSb)13 superlattice grown by molecular beam epitaxy for infrared detector applications has been investigated using high resolution X-ray diffraction. X-ray diffraction reciprocal space maps exhibit distinct lateral satellite peaks about the vertical superlattice peaks; however, the pattern is tilted with respect to the (001) direction. This tilt is directly related to the stacking of the layers as revealed by cross-sectional scanning tunnelling microscopy (XSTM) images. XSTM shows the morphology of the structure to consist of InAs- and GaSb-rich regions with a modulation wavelength of ~1200A and a lateral composition wavelength of 554 +/- 3 A. The modulation only occurs along one in-plane direction, resulting in InAs 'nanowires' along the [11 0] direction, which are several microns long.
Pub. in Jnl. of IEE Proc.-Optoelectron, v150 n4 p420-423, Aug 2003. Sponsored in part by the Office of Naval Research and DARPA.