First-principles study of InAs, InxGa1-xSb nanotubes and InAs/InxGa1-xSb nanotube superlattices

Semiconductor InAs, GaSb and InAs/InxGa1-xSb superlattices have been used for optoelectronic devices in a wide infrared region from near to long wavelength infrared. The efficiency of these devices could be increased shrinking the size and modifying the constituent structure. Nanostructured materials are natural candidates for these applications. We have implemented first-principles theory to investigate the structural and electronic properties of (10,0) InAs, GaSb, InxGa1-xSb nanotubes and InAs/InxGa1-xSb nanotube superlattices. The InAs and GaSb nanotubes exhibit direct band-gaps of 0.24 and 0.41 eV. The InxGa1-xSb nanotubes also exhibit direct band-gaps for the whole range of In compositions, with "scissor" modified band-gap varying from 0.56 to 0.15 eV, and a negative band-gap bowing coefficient of -0.15 eV. The InAs/InxGa1-xSb nanotube superlattice shows a type-II broken-gap band alignment, and the band-gap explicitly varies with the superlattice period and alloy concentration x. The results indicate the possibility of engineering the band-gaps of InAs/InxGa1-xSb nanotube superlattices by adjusting nanotube segment length and alloy concentration of constituent materials. (C) 2011 Elsevier B.V. All rights reserved.