1. Université Côte d’Azur, CNRS, Centre de Recherche sur l’Hétéro-Epitaxie et ses Applications, Rue Bernard Gregory, Sophia Antipolis, 06560 Valbonne, France.
2. Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, CA 94720, USA.
3. Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.