Uniaxial Stress-Modulated Electronic Properties of a Free-Standing InAs Nanowire

A tight-binding sp(3)d(5)s* orbital basis quantum simulation is performed to study the uniaxial stress-modulated electronic properties of an InAs nanowire in three different crystallographic directions. Over the entire range of axial stress used in this study, the wire exhibits a direct band gap under uniaxial stress in < 100 > and < 111 > directions; however, a direct to indirect transition is observed in < 110 > direction at a relatively large tensile stress. The band gap variation with stress is linear in < 100 > and < 111 > directions, and the gap is relatively insensitive to external stress in < 110 > direction. However, after the direct to indirect transition in < 110 > direction, the band gap is reduced with stress. The electron and hole effective masses show the highest dependence on external stress in < 100 > direction, and a big jump in the hole effective mass is observed in < 100 > and < 110 > directions under tensile stress. From the projection of normalized wave function to different orbitals, it is found that the direct to indirect transition in < 110 > direction and the discontinuity in the hole effective mass in < 100 > and < 110 > directions result from the change in top valence band wave function symmetry.