Nanowire unter tensile strain

01.10.2011 - 30.09.2014
Research funding project
Today, most modern technology relies on materials with reduced dimensionalities, such as thin films (2D), nanowires (1D), and quantum dots (0D). An extreme success in synthesis, characterization, and application has been achieved within the past 30 years. Although the electrical and optical properties of nanostructures have been extensively studied, the effects of high mechanical strain levels on the electronic and optical properties have been largely overlooked up to now. In situ tuning of high strain levels has proved to be challenging. The nanostructures have to be interfaced with electrodes which guarantee reliable contacts even when subjected to such mechanical forces, where surface imperfections may initiate fractures. Most of the approaches, such as the commonly used four point bending method, are applicable to study e.g. the piezoresistive behavior of NWs only at low strain levels. Therefore we merge: (a) on the personal level two important research groups out of Japan and Austria, as well as (b) on the scientific level bottom up and top down techniques: self assembled synthesis of NWs via the vapor-liquid-solid growth mechanism and a highly sophisticated electrostatic actuated nano tensile testing device. Thus, we explore a special setup that enables the application of pure tensile strain without a shear component while measuring simultaneously the electrical and optical properties of thereby ultra-strained NWs. The synthesis techniques will be based on the vapor-liquid-solid process to integrate well defined nanowires within the electrostatic actuated nano tensile testing device. Such nanowires appeared to be relatively free of extended volume defects and may withstand high stress levels before the strain will be relieved by the formation of dislocations and other defects. The ability to fabricate single-crystal NWs that are widely free of structural defects will it make possible to apply ultra-high strain without fracturing, therefore in any application where crystallinity and strain are important, the idea of making NWs should be of a high value. Such strained nanowires in the electrostatic actuated nano tensile testing device will be subjected to various analysis techniques like field emission scanning electron microscopy, µ-Raman spectroscopy, spatially resolved photoluminescence as well as temperature dependent electrical transport investigations. Three promising systems will be investigated within our research: (i) Si-, Ge- and SiC-nanowires, (ii) the respective silicides and germanides of Pt, Ni and Co, and (iii) axial NW heterostructures such as NiSi/Si/NiSi-NWs. The main focus of this project is the investigation of the correlation between strain and functionality of the NWs, in view to enable novel electronic, photonic, or ferroic devices. A long term goal of the project includes the realization of a prototype of silicon-compatible strain gauges or a high performance piezoelectric MOSFET device.

People

Project leader

Project personnel

Institute

Grant funds

  • FWF - Österr. Wissenschaftsfonds (National) Austrian Science Fund (FWF)

Research focus

  • Special and Engineering Materials: 50%
  • Nano-electronics: 30%
  • Climate Neutral, Renewable and Conventional Energy Supply Systems: 20%

Keywords

GermanEnglish
Nanodrahtnanowire
Verspannungstrain
MEMSMEMS
Siliziumsilicon
GermaniumGermanium
Ramanraman

Publications