Strain and anisotropy effects studied in InAs/GaAs(2Â 2Â 1) quantum dashes by Raman spectroscopy

Quantum dashes were synthesized in the molecular beam epitaxial growth of InAs on GaAs(2 2 1). By changing the arsenic pressure it was possible to obtain highly ordered one-dimensional InAs arrays as demonstrated by autocorrelation function analysis. Polarized Raman spectroscopy was utilized in order to characterize the samples and to estimate the stress at the InAs/GaAs interface as well as the surface anisotropy imposed by the quasi one-dimensional character of the quantum dashes. The most ordered surface, showed the lowest correlation length, and for this sample the Raman spectra exhibits small shift of the GaAs resonance modes indicating likewise small GaAs tensile strain.