Berlin 2012 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 33: Ge/Si II

HL 33.3: Vortrag

Dienstag, 27. März 2012, 10:00–10:15, EW 015

Probing local strain and composition in Ge nanowires by means of tip-enhanced Raman scattering — •Juan S. Reparaz^1,2, Niculina Peica¹, Ronny Kirste¹, Alejandro R. Goñi^2,3, Gordon Callsen¹, Markus R. Wagner¹, Maria I. Alonso², Miquel Garriga², I. Carmen Marcus², Isabelle Berbezier⁴, Jannina Maultzsch¹, Christian Thomsen¹, and Axel Hoffmann¹ — ¹Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstr. 36, u o a 10623 Berlin, Germany — ²Institut de Ciència de Materials de Barcelona-CSIC, Esfera UAB, 08193, Bellaterra, Spain — ³ICREA, Passeig Lluís Companys 23, 08010 Barcelona, Spain — ⁴IM2NP, CNRS - Univ. Aix Marseille, Campus St. Jèrôme, Case 142, 13397 Marseille Cedex 20, France

In this work we investigate local strain and composition in Ge nanowires using tip-enhanced Raman scattering (TERS). We will mainly focus on the influence of the tip on the NW's Raman spectrum, showing that the electromagnetic field enhancement due to the TERS effect allows to probe the local composition and strain in these nanostructures. A close comparison with what can be achieved using micro-Raman will be discussed, showing the great advantages of TERS over conventional far-field optical techniques. As a striking result we will show the presence of local vibrational modes (LVMs) of the GeGe mode in the presence of a Au rich enviroment which acts as catalyst for the NWs growth, are only observed using TERS. Finally, the dependence of strain and composition with the position along the NWs will be presented.