Ab initio study of strained wurtzite InAs nanowires: engineering an indirect-direct band gap transition through size and uniaxial strain

This work is focused on the dependence of electronic properties of wurtzite InAs [0001] nanowires on their size and under uniaxial strain using ab initio calculations. Diameter and strain are studied up to 3.0 nm and 8% respectively. We found that the band gap can be modulated by varying the size of the nanowires and applying strain to them. The band gap increases with the decrease in diameter of the wires and the change in the band gap compared to the bulk is directly proportional to 1/D-2. There is an indirect-direct band gap transition with changes in diameter and applied strain. The critical value of the diameter and strain for the indirect-direct band gap transition is 2.0 nm and 5.5%, respectively. This indirect-direct band gap transition can make InAs nanowires an optically active medium and hence useful in optoelectronics and light emitting devices.