1. Faculty of Materials Science and Engineering, Jimma Institute of Technology, Jimma University, P. O. Box 378, Jimma, Ethiopia
2. Department of Physics, College of Natural and Computational Science, Mizan-Tepi University, P. O. Box 260, Mizan, Ethiopia
3. School of Chemical Sciences, Mahatma Gandhi University, Kottayam 686560, India
4. Department of Physics and Mathematics, Università Cattolica del Sacro Cuore, Via della Garzetta, 48, 25133 Brescia, BS, Italy
5. Department of Physics, Baselius College, Kottayam 686001, India
6. School of Energy Materials, Mahatma Gandhi University, Kottayam 686560, India
7. Department of Materials Science and Engineering, Adama Science and Technology University, P. O. Box 1888, Adama, Ethiopia
8. Center of Advanced Materials Science and Engineering, Adama Science and Technology University, P. O. Box 1888, Adama, Ethiopia