Jean-Claude Gerbedoen,

the rich and diversified course a maturation engineer at IEMN

It is during his year of DESS (Master pro) in MRH (Microwave, Radio- and Hyperfrequency) during a 4 months internship at OMMIC in the Paris region that Jean-Claude discovers the world of the clean room and takes a liking to it by setting up a characterization bench for HBT (Heterojunction Bipolar Transistor) transistors. Fascinated by research and the possibility of creating his own components, he validated a year of DEA (Master Research) and continued on to a doctorate.

Fig. 1: FIB image of a cross-sectional view of a transistor with a debonded nitride gate.

Throughout his thesis, which he carried out in the PUISSANCE team of the IEMN from 2005 to 2009 under the direction of Jean-Claude De Jaeger and supervised by Ali Soltani, he extended his knowledge and mastery of transistors (Fig.1).

For his subject financed by a DGA (Délégation générale de l'Armement) grant, he designs, realizes and characterizes HEMT (High Electron Mobility Transistor) transistors on low-cost silicon substrates, for mobile telephony and satellite communication applications in order to get the best possible performances. At the same time, he broadens his skills by training in new equipment through related projects:

Fig. 2: SEM image (left) and optical image (right) of MSM produced by optical lithography with a diameter of 1mm².

- Fabrication of MSM (metal/semiconductor/metal junction) photodetectors on large Gap materials for space applications in the framework of the K-star project in collaboration with the ROB (Fig. 2).

- development of a process to improve the spreading of resins for lithography steps

Once the thesis is in his pocket, a future full of opportunities is offered to him in the form of three postdoctorates!

The big gap in Canada

In 2009, the University of Sherbrooke in Canada, Quebec recruited him for two years to develop large gap transistors. He then completely redeveloped the manufacturing chain for hybrid vehicles. He uses AlGaN/GaN epitaxy on SiC (Silicon Carbide) substrate for its better power performance and stability.

In parallel to his main mission, he continues to train for new experiences:

- it is developing GaN-based UV and blue LEDs for use in skin treatment

- he supervises students at the end of their engineering cycle to develop characterization benches for HEMT AlGaN/GaN transistors, characterize etchings of the same material and LEDs.

IEMN comeback

For his second post-doc, he rejoins the PUISSANCE team in 2011 and works on an ANR project Deltadiam in collaboration with ESRF, CEA Saclay and the NĖEL institute in Grenoble. He resumes the processes of his thesis but this time for all-diamond transistors and material characterization patterns (Hall bars) in electron lithography (Fig.3) on single-crystal diamond substrates of very small dimensions (2x2mm² and 3x3mm²).

Fig. 3: SEM (left) and optical (right) images of Hall bars after complete manufacturing process on single-crystal diamond.

His third post-doc from 2012 to 2015 which offers him the opportunity to diversify his skills in the AIMAN-FILMS team on an ANR project Livecams. Turning to fluid mechanics and more particularly flow control, he designs and characterizes actuators called synthetic jets (Fig. 4) that are placed at the rear of a vehicle in order to optimize its aerodynamics. Indeed, active flow control by synthetic jets, characterized by a blowing phase and a suction phase, aims to modify the vortices that form at the rear of a vehicle during its movement and to reduce in fine fuel consumption. Fabrication of more than 120 actuators with packaging, on 4-inch silicon substrates, was required for this project.

Fig. 4: Complete actuator (Synthetic Jet) and packaging

This industrial-oriented project coordinated by Philippe Pernod was then part of a public-private partnership with the PSA Peugeot Citroën group.

It associates several organizations:

- IEMN for the design, realization and characterization of MMEMS (Magneto-MicroElectroMechanical Systems) jet arrays (Fig. 5 left)

- The PRISME laboratory (Pluridisciplinary Research Laboratory in Systems Engineering, Mechanics, Energy) in Orleans for the provision of the wind tunnel and the manufacture of the vehicle model (Fig. 5 right)

- the laboratory of Mathematics Jean Alexandre Dieudonné (LJAD) in Nice for the numerical simulation part on model.

Fig. 5: Installation of a network of MMEMS JS on a base: left, assembly of 24 JS on an actuator holder - right, diagram of the model with interchangeable base used in the wind tunnel.

After a teaching position as an ATER for a year at Centrale Lille and after having trained a post-doc and a PhD student in clean room on the realization of multiphysics sensors measuring temperature, pressure and velocity, he is recruited the SATT Nord (Société d'Accélération du Transfert de Technologie) in 2016 on a CDI Chantier for a position of maturation engineer where he participates in the development of a focused-wave acoustic clamp using the properties of a piezoelectric material (Fig. 6) as part of the Acoustipince project (see p. 14: https://www.satt.fr/wp-content/uploads/2018/01/rapport-dactivite-pdf-interactif-2016.pdf) at the IEMN Level 2 Biology laboratory for non-contact manipulation of micro-objects (polystyrene beads) and, eventually, living cells, in collaboration with biologists. The system can be adapted to inverted microscopes.

Fig. 6: Focused wave acoustic clamp (Acoustipince project)
Photo of the acoustic clamp and schematic diagram of a focused wave vortex

This work is carried out under the direction of Ms. Ouafae Cohin, project leader on the SATT * Nord side and Michaël Baudoin, project leader on the IEMN side.

In conclusion, his pleasure in designing and mastering a wide range of technological processes and machines has allowed Jean-Claude to shape a multi-faceted career path. It is quite natural that he turned to his current maturation project - an interdisciplinary project that offers prospects for industry or start-ups. To carry out this project, Jean-Claude, like any good researcher and especially for this project, uses his creativity, responsiveness and adaptability on a daily basis. In order to meet the deadlines, he must also be autonomous during each phase of the development chain and be a good communicator. We can also add another valuable quality that allowed us to draw up this portrait: his sense of collaboration.

And to close this work, here is a quote from Jean-Claude, both theoretical and practical, to be meditated without restriction for researchers but also in everyday life:

"For every problem, there is at least one solution. And, finding as many solutions as possible allows you to choose the best one."

* The SATT emerged from the "investments of the future" program launched by the government in 2010 in the form of calls for projects to increase innovation in France. Part of a national network of 14 entities, the Société d'Accélération du Transfert de Technologie du Nord, which has covered the upper part of the territory (Hauts-de-France and Champagne Ardennes) since 2012, supports laboratories in the development of their projects. With a multidisciplinary team (project managers, business managers and legal experts), it applies its know-how to the maturation of projects, applied to the entire R&D chain, supporting its expertise at each phase of development, from the detection of innovation potential and the analysis of patentability for which it drafts intellectual property reports to the marketing of the technique or product.

(c) Author: Karine Perrot - IEMN-ECM