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Funding available for:
Enthusiastic, motivated individuals interested in joining the research activities of the
Group should have a BSc (Hons), Masters or PhD qualification. Participation in any
of the projects listed below will lead to a higher degree, except in the case of PhD
graduates for whom a limited number of Post-Doc positions are available.
Befondsing beskikbaar vir:
Entoesiastiese, gemotiveerde indiwidue wat belang stel om by die navorsings-aktiwiteite van hierdie groep in te skakel, moet in besit wees van 'n BSc (Hons), Meesters of PhD kwalifikasie. Deelname aan een van die projekte sal lei tot die verkryging van 'n höer graad, behalwe in die geval van persone met 'n PhD waarvoor 'n beperkte aantal na-doktorale studentskappe besikbaar is.
Introduction
Research Projects
1. Influence of process induced defects on quality of electronic devices.
Contact: fauret@scientia.up.ac.za
2. Radiation- and processing-induced defects in GaAs.
Contact: fauret@scientia.up.ac.za
3. Optimization of metallisation procedures for group IV-IV
semiconductors.
Contact: fauret@scientia.up.ac.za
4. Micro-structural investigation of steels.
Contact: gmyburg@scientia.up.ac.za
5. Sputter deposition of thin films.
Contact: gmyburg@scientia.up.ac.za
6. Conducting Polymers:
Contact: sgoodman@scientia.up.ac.za
7. Gallium Nitride:
Contact: sgoodman@scientia.up.ac.za
8. Influence of rare earth doping on the photoluminescence and electrical properties of semiconductors:
The interaction of ions with semiconductors is being modeled using
programs like TRIM and MARLOWE to investigate ion- and defect
distributions. In particular, the effect of noble gas ions in GaAs is being
investigated as function of ion energy and crystal orientation. In 1999 we
shall extend this research to SiGe. This project is partly funded by the
bilateral Flemmish/SA agreement and makes provision for student and
personnel exchange.
Contact: sgoodman@scientia.up.ac.za
9. Any projects related to these above will be considered.
Contact: fauret@scientia.up.ac.za
This research group in the Physics Department is internationally recognized for its
research related to the fabrication and characterization of ohmic and Schottky
contacts to several different semiconductors and characterization of
process induced defects in semiconductors. Numerous publications have
emanated from their research. Currently, the group is also
expanding its research activities to conducting polymers and stainless steels.
During several device processing steps the semiconductor is intentionally or
unintentionally exposed to a variety of particles (ions and neutrons) with
energies ranging from a few eV to hundreds of MeV. These particle-induced
defects can have a profound influence on the semiconductor properties and
on the characteristics of devices fabricated on it. In order to avoid the
deleterious effects of some of these defects and utilise the beneficial effects
of others, depending on the application, it is imperative to understand the
effect of radiation on electronic materials and devices fabricated on them. To
achieve this, it is essential that the electronic properties and concentration of
radiation induced defects should be known, allowing calculation of their
effect on the properties of electronic materials and devices. In addition, the
structure, introduction rate, introduction mechanism and thermal stability of
the defects should be determined so that they can be reproducibly
introduced, avoided or eliminated, depending on the application. Deep level
transient spectroscopy (DLTS), which allows independent studies of different
defect species in the same semiconductor, has been a key characterisation
technique in providing most of this information.
GaAs has several different applications, ranging from solar cells for space
applications to high frequency (terahertz) oscillators. These oscillators have,
amongst others, been used to monitor the ozone layer. Particle implantation
has been shown to reduce carrier lifetimes in semiconductors and can
therefore be used to render materials suitable for fast switches. DLTS in
conjunction with I-V and C-V measurements are used to investigate the
defects introduced in GaAs during exposure to a variety of particles with
energies ranging from a few hundred eV to several hundred MeV. In this
project, some measurements are being done using the latest DLTS
technology, i.e. Laplace-DLTS, for defect characterisation.
Current trends towards low power electronic devices and plans for
optoelectronic integrated circuits (OEICs), have created significant interest in
SiGeC/Si heterostructures. These structures offer a number of advantages
that could lead to the improvement of several electronic devices. One of the
most important aspects of realizing the potential of SiGeC devices is the
preparation of high quality metal contacts to this material. The ultimate
performance of the devices critically depends on metallisation related
processing steps, such as dry etching, metallisation and annealing. DLTS in
conjunction with I-V and C-V measurements is used to investigate the effect
of the defects introduced during these processes on the quality of Schottky
barrier diodes in Si, SiGe and SiGeC. The noise "introduced" in the diode
characteristics by process induced defects is also being investigated. This
project is partly funded by the bilateral FRANCO/SA agreement and makes
provision for student and personnel exchange.
This project will include TEM and SEM investigation of Ru and Ag containing
stainless steels. It has been shown that small additions of Ru and Ag
improve the corrosion behaviour of stainless steels in reducing acid media.
It is well known that sputter deposition results in good adhesion of thin films.
In this project the sputter deposition will be used to deposit thin films on
various substrates, including semiconductors, stainless steels and polymers.
The quality of the deposited layer(s) will be determined as function of sputter
deposition conditions, substrate and metal type, metal combinations, and
gas species and pressure for various applications.
With the recent developments in the field of plastics that conduct electricity,
this field of research is receiving much attention from both a fundamental
and applied perspective. Many leaders in the field of "new" technologies are
investing in these promising new materials. Our planned contribution to this
field will be in contact fabrication and material characterization (electrical).
The success of the Nichia Chemical company in developing stable blue
LEDs for commercial use further created interest in this wide band gap
material. The newly developed GaN LEDs allow the production of full colour
displays. The development of these blue emitters will lead to the
improvement and development of technologies such as colour photocopiers,
scanners and facsimile machines. The use of expensive filters is also
eliminated when using LEDs. A further, exciting use of blue/green LEDs is
in the field of optical writing and reading of data in compact disk memories
and opto-magnetic memories. Using the shorter wavelength blue LEDs will
increase the storage density by about a factor of four compared to the red
lasers currently in use. We have been actively involved in this project with
international partners in Germany and France since early 1998. We have
concentrated on defect characterization (process induced and particle
irradiation). Our future plans involve expanding our present thrust as well as
looking at cleaning procedures, contact fabrication and surface analysis.
In the last two years rare earth doped semiconductors have received world
wide attention because of possible applications in optoelectronics. This
combination of rare earth elements as dopant atoms incorporated into a
semiconductor provides a system which exhibits a temperature stable
luminescence wavelength which is nearly independent of the specific
semiconductor host. The development of fibre-optic communication systems
has stimulated a growing interest in temperature-stable light sources
emitting at 1.54 µm. This wavelength is achieved with minimum loss using
silica based optical fibres. This could lead to the development of novel
electroluminescent devices which combine the favourable properties of
semiconductors with the unique luminescent features of rare earth ions.
However, the low solubility of optically active Er3+ and the long radiative
lifetime, the luminescence yield is only moderate at low temperatures. This
implies that devices operating at room temperature have insufficient
emission. Therefore there are still exciting challenges in order to have a
detailed understanding of the incorporation of Er in the host lattice and the
processes responsible for the emission efficiencies.
last updated: 16 February 2000
Maintained by:
Michael Hayes - mhayes@scientia.up.ac.za
© Department of Physics, University of Pretoria