Carbon Nanotubes are thin molecular wires which consist only of sp2 hybridized carbon tubes. Depending on their structure they can be semiconducting or metallic. In our group we prepare those tubes by chemical vapor deposition techniques and explore their properties by confocal Raman and fluoresecence spectroscopy of individual tubes. Further we electrically contact individual tubes by lithographic techniques to investigate their electrical properties and also use them as templates for electrochemical deposition of nanomaterials.
Current Projects Focus on:
- Synthesis of Carbon Nanotubes
- Raman and Fluorescence Spectroscopy
- Electrical Transport and Photo Conductivity
Carbon nanowalls (CNWs; sometimes also denoted as carbon nanoflowers, petals or flakes) can be described as two-dimensional graphite nanostructures with edges comprised of stacks of plane graphene sheets standing (almost) vertically on the substrate. These sheets form a wall structure with a high aspect ratio. The thickness of CNWs ranges from under one nanometer to a few tens of nanometer.
Figure 1: Schematic composition of carbon nanowalls 
For synthesis we use a radio frequency (RF = 13.56 MHz) capacitively coupled plasma enhanced chemical vapor deposition (CC-PECVD). The central part is a vacuum reaction chamber with a fast heating stage and two electrodes for plasma generation. Several mass flow controllers are used to adjust the ratio of carbon precursor (CH4, C2H2, C2H4), etchant (H2, H2O) and auxiliary gas (Ar, He).
(1) upper electrode, (2) substrate, (3) heating Plate, (4) lower electrode, (5) power line, (6) temperature sensor
CNWs can be homogeneously grown by PECVD over large areas (4 cm2) at low temperatures (∼500 °C) without catalyst. Structural analysis is done by several methods, mainly SEM, Raman and conductivity measurements.
Figure 3: SEM surface (a) and cross sectional (b) scan of CNWs
Newest research projects on CNWs are:
Figure 4: SEM image of CNWs with metal nanoparticles
- Investigation of the growth mechanism
- Electrochemical modifications and measurements
 Kurita, S., A. Yoshimura, H. Kawamoto, T. Uchida, K. Kojima, M. Tachibanaa, P. Molina-Morales, and H. Nakai, Raman spectra of carbon nanowalls grown by plasma-enhanced chemical vapor deposition. Journal of Applied Physics, 2005. 97.