Effects of stacking variations on the lattice dynamics of InAs nanowires

The optical phonon properties of single InAs nanowires and their relation to the crystal structure are studied by means of Raman spectroscopy. The nanowires were grown by molecular beam epitaxy on Si (111) without foreign catalyst and exhibit variations in the stacking sequence with wurtzite and zincblende inclusions. Specific new features, such as a TO frequency shift and selection rules different from bulk InAs, are observed. Further polarization-dependent measurements reveal the existence of four individual peaks in the optical phonon energy range of InAs. By performing a full azimuthal-dependence analysis of the Raman scattering intensity, the individual symmetry behavior of these peaks could be determined, namely the B1H, E2H, TO (A₁ + E₁), and LO (A₁). The B1H and E2H modes are assigned to wurtzite-type modes.