Final Report Summary - LASEM (Light assisted single electron manipulation)
Executive Summary: (Project acronym: LASEM)
The LASEM project in general had technological, scientific and reintegration goals. The technological aspect of the project was aimed at development and implementation of nanofabrication techniques. The scientific aim of the project was related with the study of electron transport in hybrid nanodevices based on carbon nanotubes (CNT) and quantum dots (QDs). Finally, the reintegration goal was related to the integration of the fellow with the host institute, including longtime employment, research team and lab facilities building.
The goal of the technological aspect of the project was to fabricate nanodevices that consists of carbon nanotubes field effect transistor combined with quantum dots. This involves several achievements. First, homemade CVD system for high quality nanotubes production has been installed and implemented. Second, the techniques of nanotubes separation and QDs deposition have been developed. Next, advanced method for thin nanotubes films has been worked out. All the devices was produced using AFM, e-beam lithography and Raman spectroscopy. As a building block individual single-walled semiconducting CNTs, thin CNT films, and various quantum dots (e.g. CdSe, Au, TiO2) have been used.
In addition, the project has been a motivation for further development of the scientific infrastructure - both new equipment and new lab space has been acquired in order to continue the work stared by the LASEM project.
The scientific aim of the project was to study single electron manipulation in nanodevices subjected to external perturbation such as light and electric field. A few important achievement can be mentioned:
- The possibility to observe the electron transfer and detection at room temperature has been shown. The detection scheme is based on the fact that electrons can tunnel between quantum dots and the nanotube, which serves here as a detector. Electron jumps between these nanoobject are detected by means of electron counting spectroscopy.
- The study of the effect of light on the transport properties of nanotube devices. The change of the current (>5%) upon light exposure has been measured. The interplay between photovoltaic and heating effect has been observed.
- New method of the CVD growth of carbon nanotubes has been developed. The novelty is the use of propane as carbon precursor.
- The demonstration of the absorption anisotropy in the individual carbon nanotubes has been investigated. The study shows that upon linearly polarized light the photoresponse of the tubes can be significantly different.
These study are important for development novel sensitive, efficient and broadband photovoltaic or photo-detector devices.
The scope of the study covered by the LASEM project had strong interdisciplinary aspect because it brings together different field of expertise, e.g. nanotechnology, physics, molecular electronics, optoelectronics and chemistry.
The research is (and will be) further continued by the researcher. New publication from the LASEM results are still in preparation.
The reintegration goal of the project has many aspect that are extremely important for the potential future of the Marie Curie fellow.
First of all the fellow is currently the leader of the Nanostructures group at the Faculty of Physics WUT. The LASEM project gave substantial support for reaching this position. The group has now at its disposal new facilities space (offices, characterization lab, chemistry lab and nanolithography lab) that is necessarily to lead the group and continue the research.
The subject of the LASEM project attracted many students (4 PhD students, 5 MSc students) and permanent stuff that joined the group. Further, the research activity of the fellow strongly pushed forward the collaboration with other groups and institutions, what resulted in initiation of new projects with new partners. By now the fellow is involved in several national/international projects and long-term collaboration.
During the time of the project the fellow was awarded by few national awards for young scientist.
Contact:
Mariusz Zdrojek, PhD
Head of Nanostructures Group
Faculty of Physics, Warsaw University of Technology
zdrojek@if.pw.edu.pl