Flat and twin-free InAs layer growth on Ge (1 1 1) substrates

Abstract

After the growth of GaSb buffer layers using Bi as a surfactant, InAs layers were grown by molecular beam epitaxy on Ge (1 1 1) vicinal substrates. The effects of the As beam pressure and the substrate temperature on the surface morphology and the twin generation have been investigated by atomic force microscopy and X-ray diffraction, respectively. It has been shown that, in spite of the rather rough surface of the GaSb buffer layer, a flat and twin-free InAs layer can be grown by adopting the appropriate As beam pressure and substrate temperature for the InAs growth. The use of the InAs flattening layer together with the GaSb twin suppression layer is expected to open the possibility of manufacturing devices for which flat interfaces are vital, e.g., InAs/GaSb superlattice infrared detectors, InAs based hetero-structure field-effect transistors, and so on.