Optical properties of Zn doped GaP single crystals M. M. El-Nahass, H. S. Metwally, H. E. A. El-Sayed, F. Abd El-salam and H. A. Hassan Eur. Phys. J. Appl. Phys., 43 1 (2008) 31-36 Published online: 19 June 2008 DOI: 10.1051/epjap:2008137