Nano Express
Polarized photoreflectance and photoluminescence spectroscopy of InGaAs/GaAs quantum rods grown with As2 and As4 sources
1 Optoelectronics Department, Semiconductor Physics Institute, Center for Physical Sciences and Technology, A. Goštauto 11, Vilnius, 01108, Lithuania
2 School of Electronic and Electrical Engineering, University of Leeds, Leeds, LS2 9JT, UK
3 CSIR-National Physical Laboratory, 110012, Dr. K. S. Krishnan Marg New Delhi, India
Nanoscale Research Letters 2012, 7:609 doi:10.1186/1556-276X-7-609
Published: 5 November 2012Abstract
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 As2or As4sources. 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 
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 
-cleaved surfaces (TM[001]>TE[110]), whereas the transverse electric mode prevailed for (110)-cleaved surfaces (
). This strong optical anisotropy in the (001) plane is interpreted in terms of the
hole wavefunction orientation along the 
direction for high aspect ratio QRs.
