Project

Discipline

semiconductor nanowire; one-dimensional structure; doping; nanowire; molecular beam epitaxy; III-V semiconductors

Lead
Lay summary
Semiconductor nanowires constitute one of the most promising building blocks for next generations of electronic and optoelectronic devices. As a consequence of the small size and large surface-to-volume ratio, the functionality of these nanostructures is increased with respect to a bulk semiconductor. Key issues for their future application in real devices are: the improvement of crystalline quality and purity, the ability of combining different materials in one same nanostructure in a desired geometry and composition, doping for the control of the electrical conductivity and fabrication of devices as well as the development of self assembly method that avoids the intensive use of lithography at the nanoscale level. Nowadays, one of the critical issues for the device application of nanowires is the precise control of the conductivity by impurity doping.This proposal is devoted to realize and control doping in high quality III-V nanowires synthesized by Molecular Beam Epitaxy (MBE) without the use of an external catalyst. The project is organized around two main aspects, the synthesis and the investigation of the structural and functional properties. We want to answer the following questions:•How can one efficiently incorporate dopants in III-V nanowires with MBE methods?•What are the limits, in terms of concentrations, homogeneity and dimensions of the nanowires?•What are the consequences for the structural and electronic properties?Two different doping strategies will be investigated. The first one is the incorporation of dopants -mainly Si and C- during growth, while the second one considers the introduction of the doping atoms a posteriori by growing on the facets of the nanowires. The samples will be characterized both from the structural and functional point of view. The main techniques that will be used are: Transmission Electron Microscopy, Raman Spectroscopy, electronic transport measurements as a function of magnetic field and temperature from room temperature down to at least 4,2 K.Unique in this project is the use of MBE for the fabrication and doping of nanowires. Our technique avoids any contamination such as the use of gold as nucleation seed -as it is usually the case in other growth methods. Since three decades MBE is known to push the frontiers in research and development of planar semiconductors heterostructures due to the ultra high vacuum environment, atomically precise layer growth and band gap engineering [ ]. Many exciting physical phenomena like Aharonov-Bohm oscillations, coherence, electron interactions or correlations and coulomb blockade will have an ideal frame to be investigated. Equally important, by effective doping novel devices will be demonstrated. We expect as a result a new frame which offers new perspectives for research on one dimensional structures.

Direct link to Lay Summary

Last update: 21.02.2013

Active participation

Number	Title	Start	Funding scheme

Semiconductor nanowires constitute one of the most promising building blocks for next generations of electronic and optoelectronic devices. As a consequence of the small size and large surface-to-volume ratio, the functionality of these nanostructures is increased with respect to a bulk semiconductor. Key issues for their future application in real devices are: the improvement of crystalline quality and purity, the ability of combining different materials in one same nanostructure in a desired geometry and composition, doping for the control of the electrical conductivity and fabrication of devices as well as the development of self assembly method that avoids the intensive use of lithography at the nanoscale level. Nowadays, one of the critical issues for the device application of nanowires is the precise control of the conductivity by impurity doping.This proposal is devoted to realize and control doping in high quality III-V nanowires synthesized by Molecular Beam Epitaxy (MBE) without the use of an external catalyst. The project is organized around two main aspects, the synthesis and the investigation of the structural and functional properties. We want to answer the following questions:•How can one efficiently incorporate dopants in III-V nanowires with MBE methods?•What are the limits, in terms of concentrations, homogeneity and dimensions of the nanowires?•What are the consequences for the structural and electronic properties?Two different doping strategies will be investigated. The first one is the incorporation of dopants -mainly Si and C- during growth, while the second one considers the introduction of the doping atoms a posteriori by growing on the facets of the nanowires. The samples will be characterized both from the structural and functional point of view. The main techniques that will be used are: Transmission Electron Microscopy, Raman Spectroscopy, electronic transport measurements as a function of magnetic field and temperature from room temperature down to at least 4,2 K.Unique in this project is the use of MBE for the fabrication and doping of nanowires. Our technique avoids any contamination such as the use of gold as nucleation seed -as it is usually the case in other growth methods. Since three decades MBE is known to push the frontiers in research and development of planar semiconductors heterostructures due to the ultra high vacuum environment, atomically precise layer growth and band gap engineering [ ]. Many exciting physical phenomena like Aharonov-Bohm oscillations, coherence, electron interactions or correlations and coulomb blockade will have an ideal frame to be investigated. Equally important, by effective doping novel devices will be demonstrated. We expect as a result a new frame which offers new perspectives for research on one dimensional structures.