"Spicy world of NanoScience"
AHLAL Mohamed, ZORKANI Izeddine, Jorio Anouar
Laboratory of Physical State, Faculty of Sciences Dhar El-Mahraz University Sidi Mohamed Ben Abdellah, Fez, Morocco
Silicon carbide (SiC) is regarded today as a semiconductor material key to the development of a specific electronic high temperature, high power and high frequencies.
However, in the field of optoelectronics, this material has generated only lukewarm interest because of the indirect nature of its band gap is responsible for a weak luminescence at room temperature. However, like silicon, the nanostructuring of the material involves a considerable strengthening of its light emitting properties.
We propose in this thesis to conduct a study of optical properties of SiC nanostructures.
We are particularly interested in this study to bringing to light the quantum confinement effects in the photoluminescence of these nanostructures.
Our study is also an opportunity to relate the information on the electronic, structural and chemical properties of nanostructures obtained by independent techniques and their Photoluminescence properties.
One of the great difficulties that existed at the beginning of this work, the study of optical properties of nanostructures of SiC was the absence of luminescence above the gap as predicted by the theory of quantum confinement when the size of nanostructures are sufficiently small. That is why the mechanisms of luminescence associated with many defects and surface states present in
the SiC nanostructures have been considered .
During this research we have paid great attention to this issue of absence of visible quantum confinement effects in nanostructures of SiC. Thus, working with the 6H polytype, we determined that the photoluminescence in its nanostructures was the result of a competition between different mechanisms: recombination via surface states, via defect levels and impurities levels, and recombination via the confined carriers. So that quantum confinement effects clearly manifested, it is necessary to extinguish the competing mechanisms.
We propose in this thesis the use of "finite element method" to solve some problems related to the structure and geometry of SiC nanostructures.
Keywords: Nanostructures; Quantum confinement effect ; Recombination ; Photoluminescence.