1. Dipartimento di Fisica, Università di Milano-Bicocca, Piazza della Scienza 3, 20126 Milano, Italy
2. Dipartimento Scienza dei Materiali, Università di Milano-Bicocca, R. Cozzi 55, 20125 Milano, Italy
3. Plasma Sources and Application Centre, Space Propulsion Centre Singapore, 637616 NIE, Singapore
4. Electronics Materials Lab, College of Science and Engineering, James Cook University, QLD 4811 Townsville, Australia
5. School of Engineering, The Australian National University, ACT 2601 Canberra, Australia