Polarized photoreflectance and photoluminescence spectroscopy of InGaAs/GaAs quantum rods grown with As(2) and As(4) sources

We report photoreflectance (PR) and photoluminescence (PL) investigations of the electronic and polarization properties of different aspect ratio (height/diameter) InGaAs quantum rods (QRs) embedded in InGaAs quantum wells (QWs). These nanostructures were grown by molecular beam epitaxy using As(2)or As(4)sources. The impact of the As source on the spectral and polarization features of the QR- and QW-related interband transitions was investigated and explained in terms of the carrier confinement effects caused by variation of composition contrast between the QR material and the surrounding well. Polarized PR and PL measurements reveal that the polarization has a preferential direction along the [Formula: see text] crystal axis with a large optical anisotropy of about 60% in the (001) plane for high aspect ratio (4.1:1) InGaAs QRs. As a result, in PL spectra, the transverse magnetic mode dominated [Formula: see text]-cleaved surfaces (TM([001])>TE([110])), whereas the transverse electric mode prevailed for (110)-cleaved surfaces ([Formula: see text]). This strong optical anisotropy in the (001) plane is interpreted in terms of the hole wavefunction orientation along the [Formula: see text] direction for high aspect ratio QRs.