The growth of GaN nanowires surrounded by GaN/InGaN quantum wells grown by MOVPE (Metal-Organic Vapor Phase Epitaxy) has been studied extensively in the laboratory and is now well mastered . This is an important step forward as it makes possible the manufacturing and industrial production of nanowire-based LEDs for the emission of visible light (blue, green and white).
In the same way, we wish to develop new 1D nanostructures for the emission of UV light. Pioneering and promising results have been obtained in the laboratory using GaN/InAlN quantum wells grown around the GaN wires exhibiting emission at 330 nm up to room temperature . By applied a in situ annealing, we have demonstrated the possibility of etching the GaN wires core, while preserving the optical properties of the quantum wells. Thus, we made for the first time quantum well-based tubes with excellent optical properties .
The aim of the thesis is to develop new quantum wells, such as GaN/AlGaN or AlGaN/AlN grown on 1D nanostructures (wires, tubes, bands, etc.), in order to be able to reach far UV emission wavelengths (<280 nm) with the possibility destroying bacteria. This is a major challenge for the development of UV LEDs considering new applications such as water treatment or sterilization. The purpose of this study is to better understand the potentiality of 1D nanostructures to emit far UV. This type of quantum well grown on 1D nanostructures also makes possible the realization of IR subband detectors in the THz domain.
The development of several stages will be necessary to carry out this thesis project: (i) the realization of 1D nanostructures in Al(Ga)N by combining growth and selective etching, (ii) epitaxy of AlGaN-based quantum wells grown on these nanostructures, (iii) advanced structural and optical characterization, and (iv) the design of new devices and their favrication. The thesis will be based on a collaborator network (C2N, EPFL, Univ. Tyndall ...) in order to progress effectively.
The work is essentially experimental to explore fundamental phenomena at the nanometer scale while participating in a active research topic on the development of new LED devices for UV emission.
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