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

A tight-binding sp³d⁵s* 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.