1. Department of Electric Energy, Faculty of Electrical and Electronic Engineering, Escuela Politécnica Nacional, Ladrón de Guevara, Quito 170143, Ecuador
2. Department of Materials, Faculty of Mechanical Engineering, Escuela Politécnica Nacional, Ladrón de Guevara, Quito 170143, Ecuador
3. ENPHOCAMAT (FEMAN) Group, Department of Applied Physics, Universitat de Barcelona, Martí i Franqués 1, 08028 Barcelona, Spain
4. Department of Physics, Faculty of Sciences, Escuela Politécnica Nacional, Ladrón de Guevara, Quito 170143, Ecuador