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.

In this paper, we have performed first-principles calculations to study the electronic structure of single-wall (10,0) InAs, GaSb, InxGa1−xSb nanotubes and InAs/InxGa1−xSb nanotube superlattices. To representatively describe our work, the 3D illustration of the total electron density distribution on the crossing planes vertical to nanotube axis in an InAs/InxGa1−xSb nanotube superlattice (from our results) is shown below.Figure optionsDownload as PowerPoint slideResearch highlights
► InAs/InxGa1−xSb nanotube superlattices and related nanotubes are studied by first-principles.
► Band-gaps of pure InAs and GaSb nanotubes decrease as compared to their bulk values.
► A negative bowing coefficient of direct band-gaps for InxGa1−xSb nanotubes is obtained.
► InAs/InxGa1−xSb nanotube superlattices have a type-II broken-gap band alignment.
► Band-gaps of InAs/InxGa1−xSb nanotube superlattices vary with superlattice parameters.