Authors: KW Adu Q Xiong HR Gutierrez G Chen PC Eklund
Publish Date: 2006/09/26
Volume: 85, Issue: 3, Pages: 287-
Abstract
Raman scattering is shown to be an effective probe of optical and surface optical phonons in highly crystalline semiconducting nanowires SNWs We show that the confinement model of Richter et al well describes the nanowire diameter dependence of the asymmetric broadening of the onephonon band in Si nanowires observed at ∼520 cm1 We also show that the use of high laser flux ∼01 mW/μm2 leads to a second mechanism that can asymmetrically broaden the 520 cm1 Raman band This broadening has nothing to do with confinement and can qualitatively be understood in terms of inhomogeneous laser heating A model is presented that supports this explanation The production of SNWs via the vapor–liquid–solid growth mechanism leads in many cases to an instability in the nanowire diameter or crosssectional area In the second part of this review we show that this instability activates the surface optical SO phonon Raman scattering Examples of this phenomenon are shown for GaP and ZnS nanowires The former and latter have respectively cylindrical and rectangular cross sections We show that the crosssectional shape of the nanowire is important for a quantitative analysis of these SO modes
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