It is not very easy to identify relevant institutions as such in France, which you might seek contact with (CNRS and CEA mentioned above run various labs across the country covering a large range of different topics across the scientific disciplines). One reason is that individual researchers may be connected with various institutions at the same time. So, besides targeting institutions or institutes (e.g. by their name), one way to go is also to identify the people that matter to you based on their published work and to initiate contact with them.
I am assistant professor at LGEP (http://www.lgep.supelec.fr/index.php?page=scm-themes-de-recherche). Sorry the description is in French! For short, our group is specialized on semiconductor material characterization.