Influence of surface stoichiometry and quantum confinement on the electronic structure of small diameter InxGa1-xAs nanowires

Abstract

Electronic structures for In x Ga 1-x As nanowires with [100], [110], and [111] orientations and critical dimensions of approximately 2 nanometer are treated within the framework of density functional theory. Explicit band structures are calculated and properties relevant to nanoelectronic design are extracted including band gaps, effective masses, and density of states. The properties of these III-V nanowires are compared to silicon nanowires of comparable dimensions as a reference system. In nonpolar semiconductors, quantum confinement and surface chemistry are known to play a key role in the determination of nanowire electronic structure. In x Ga 1-x As nanowires have in addition effects due to alloy stoichiometry on the cation sublattice and due to the polar nature of the cleaved nanowire surfaces. The impact of these additional factors on the electronic structure for these polar semiconductor nanowires is shown to be significant and necessary for accurate treatment of electronic structure properties.

Influence of Surface Passivation on Indium Arsenide Nanowire Band Gap Energies

“…Due to the underlying polar nature of the III-V lattice, NWs with different principle axis orientations typically present surface facets with a more elaborate surface chemistry as compared to non-polar semiconductors [22]. As a result and as wellknown to researchers and technologists in this field, surface passivation of III-V semiconductors is more difficult to achieve compared to silicon surfaces.…”

“…The same pseudo-H fractional charges can be used to passivate either the GaAs or InAs NWs that are obtained by interchanging gallium with indium atoms, however each NW is relaxed independently to obtain zero strain structures. III-V materials terminated in this idealized way can readily be passivated through eliminating levels associated with a surface/interface that lie energetically within the energy band gap of the nanowire core [34]. For this study, the idealized pseudo-hydrogen terminated NWs act as a reference point to which the chemically (non-ideal) terminated surfaces can be compared.…”

“…The direct/indirect nature of the band gap is crucial for photonic device design when accompanied by strong dipole coupling matrix elements at the direct gap. Equally, the energy band gap plays a central role for nanoelectronic applications as the magnitude of the band gap determines operating voltages, the thermal operation for semiconductor transistors, and controls source-to-drain tunnelling in field effect transistors [12,22].…”

Effect of strain and diameter on electronic and charge transport properties of indium arsenide nanowires

“…Moreover, strain engineering is well known to be capable of improving charge carrier mobility in semiconducting materials 13 . However, unlike the group IV semiconductors silicon and germanium as well as their alloys, there is less known about the effect of strain on the physical properties of III-V nanowires 4,6,[14][15][16][17] , particularly in the context of nanoelectronic devices. Recently, nanowires with diameters as small as 1 nm have been fabricated relying on recent advances in bottom up as well as top down fabrication techniques.…”