Comparative optical study of epitaxial InGaAs quantum rods grown with As2 and As4 sources

Photoreflectance and photoluminescence (PL) spectroscopies are used to examine the optical properties and electronic structure of InGaAs quantum rods (QRs), embedded within InGaAs quantum well (QW). The nanostructures studied were grown by molecular beam epitaxy using As2 or As4 sources. The impact of As source on spectral features associated with interband optical transitions in the QRs and the surrounding QW are demonstrated. A red shift of the QR- and a blue shift of the QW-related optical transitions, along with a significant increase in PL intensity, have been observed if an As4 source is used. The changes in optical properties are attributed mainly to carrier confinement effects caused by variation of In content contrast between the QR material and the surrounding well.