Controlling a nanowire quantum dot band gap using a straining dielectric envelope

We tune the emission wavelength of an InAsP quantum dot in an InP nanowire over 200 meV by depositing a SiO2 envelope using plasma-enhanced chemical vapor deposition without deterioration of the optical quality. This SiO2 envelope generates a controlled static strain field. Both red and blue shift can be easily achieved by controlling the deposition conditions of the SiO2. Using atomistic empirical tight-binding calculations, we investigate the effect of strain on a quantum dot band structure for different compositions, shape, and crystal orientations. From the calculations, we estimate the applied strain in our experiment. This enables engineering of the band gap in nanowires with unprecedented possibilities to extend the application range of nanowire devices.