Raman spectroscopy of self-catalyzed GaAs 1− x Sb x nanowires grown on silicon

Thanks to their wide band structure tunability, GaAs 1− x Sb x nanowires provide exciting perspectives in optoelectronic and energy harvesting applications. The control of composition and strain of these ternary alloys is crucial in the determination of their optical and electronic properties. Raman scattering provides information on the vibrational properties of materials, which can be related to the composition and strain. We present a systematic study of the vibrational properties of GaAs 1− x Sb x nanowires for Sb contents from 0 to 44%, as determined by energy-dispersive x-ray analyses. We find that optical phonons red-shift with increasing Sb content. We explain the shift by alloying effects, including mass disorder, dielectric changes and ionic plasmon coupling. The influence of Sb on the surface optical modes is addressed. Finally, we compare the luminescence yield between GaAs and GaAs 1− x Sb...

Esther Alarcón-Lladó, Sònia Conesa-Boj, Xavier Wallart, Philippe Caroff and Anna Fontcuberta i Morral

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