[1] Research Unit of Condensed Matter, Electronic and Signal Processing, Department of Physics, Dschang School of Sciences and Technology, University of Dschang, PO Box: 67, Dschang, Cameroon
[2] Material Science Research Group, Physics Laboratory, Department of Physics, Post Graduate School, University of Maroua, PO Box: 814, Maroua, Cameroon
[3] Centre d'Etudes et de Recherches en Agronomie et en Biodiversite, Faculte d'Agronomie et des Sciences Agricoles, Universite de Dschang, Cameroun