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Reference : UMR5270-VIRLAG-005
Workplace : VILLEURBANNE
Date of publication : Monday, July 12, 2021
Scientific Responsible name : BLUET Jean-Marie
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 October 2021
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly
Description of the thesis topic
The production and sustainable management of energy are societal issues of prime importance. Today, the development of renewable energies (wind, photovoltaics...) or the deployment of electric vehicles promote a direct current distribution of energy, hence the growing demand for high voltage (HV) and / or high temperature converters. In this context of electricity transport in DC, the rise in voltage of the active components is essential in order to reduce the number of components and therefore to limit losses. Large bandgap semiconductors are a solution to achieve drastic performance improvement in power components, limited to date by the restricted properties of Silicon (Si) for these applications. The most promising materials are gallium nitrides (GaN). Compared to silicon, the main benefits brought by these materials are a good operation over a wide temperature range, a high critical electric field and a high electron drift speed leading to the capability to withstand both very high voltages, very high temperatures and to operate relatively at high frequencies [1,2,3].
The objective of the project, in which this thesis work is part, is to develop vertical GaN-based power components aiming to reach the theoretical limits of the material in terms of breakdown voltage and current in the on state. Toward this end, technological barriers such as, for example, current collapse  or the understanding of breakdown mechanisms will have to be overcome. For this, a physical characterization of the components is necessary in order to validate each step of their manufacture and operation.
The main objective of this thesis therefore includes two main parts 1) to develop methods of characterization of GaN components by coupling physical characterization methods: Deep-Level Transient Spectroscopy (DLTS), micro-Raman, photoluminescence (PL) and micro-OBIC (Optical Beam Induced Current). 2) Find links between electrical characteristics of the transistor and physical characteristics of the samples using test vehicles that will be integrated into all our manufacturing masks.
Looking further, this project will characterize GaN components in order to better understand the mechanisms at the origin of electrical limitations with the ultimate goal of improving them from a voltage resistance point of view, as well as current collapse and robustness.
 K. Chen and C. Zhou, “Enhancement-mode AlGaN/GaNHEMTand MISHEMT technology,” Phys. Status Solidi A, vol. 208, no. 2, pp. 434–438, 2011.
 J. L. Hudgins, G. S. Simin, E. Santi, and M. Asif Khan, “An assessment of wide bandgap semiconductors for power devices,” IEEE Trans. Power Electron., vol. 18, no. 3, pp. 907–914, May 2003.
 T. Nomura, M. Masuda, N. Ikeda, and S. Yoshida, “Switching characteristics of GaN HFETs in a half bridge package for high temperature applications,” IEEE Trans. Power Electron., vol. 23, no. 2, pp. 692–697, 2008.  R. Vetury, N. Q. Zhang, S. Keller, and U. K. Mishra, “The impact of surface states on the DC and RF characteristics of AlGaN/GaN HFETs,”IEEE Trans. Electron Devices, vol. 48, no. 3, pp. 560–566, 2001.
This project is part of the Vertigan project of Labex Ganext. It is an inter-laboratory collaboration between the Institut des Nanotechnologies de Lyon (INL), the Ampère laboratory and the Charles Coulomb laboratory (L2C). The PhD student will also collaborate with the laboratories in charge of epitaxial growth (CHREA) and technology (CEA-LETI).
At the Ampère laboratory, the work will be followed by Camille Sonneville (associated professor) and Dominique Planson (Professor), at the INL the supervisory team will consist of Georges Brémond (professor) and Jean-Marie Bluet (professor), and at the L2C Sandrine Juillaguet (associated professor) and Sylvie Contreras (Research Officer) will follow the work.
Constraints and risks
Journeys of several days will be planned in Montpellier at the L2C laboratory.
The candidate sought must hold a Master 2 in research and/or an engineering degree and have solid knowledge in solid state and semiconductor physics. He/she must be highly motivated by applied research. Knowledge of spectroscopic (Raman, luminescence...) and/or electrical (DLTS, micro-Obic) characterization techniques would be appreciated. He/she must possess skills to work in a team (project team), organizational skills and to report analytically and synthetically and to work quickly independently with a critical mind.
Applications must include a detailed CV; at least one reference (people likely to be contacted); a one-page cover letter; a one-page summary of the master's thesis; master 1 or 2 or engineering school grades.
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