1. Micro and Nanostructured Materials Lab (NanoLab), Department of Energy, Politecnico di Milano, Via G. Ponzio 34/3, Milano 20133, Italy
2. Institute for Microelectronics and Microsystems (IMM), Consiglio Nazionale delle Ricerche (CNR), Unit of Agrate Brianza, Via C. Olivetti 2, Agrate Brianza, MB 20864, Italy