1. ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
2. Grupo de Materiais Semicondutores e Nanotecnologia and Departamento de Física, Instituto Tecnológico de Aeronáutica, DCTA, 12228-900 São José dos Campos,Brazil
3. Department of Mechanical Engineering, Columbia University, New York, New York 10027, United States
4. Fourth Physics Institute and Research Center SCoPE, University of Stuttgart, 70569 Stuttgart, Germany
5. School for Engineering of Matter Transport and Energy, Arizona State University, Tempe, Arizona 85287, United States
6. National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
7. Centro de Física and Departamento de Física and QuantaLab, Universidade do Minho, P-4710-057 Braga, Portugal
8. International Iberian Nanotechnology Laboratory (INL), Avenida Mestre José Veiga, 4715-330 Braga, Portugal
9. ICREA—Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain