K. Talla^{1, 2,}, O. Sakho¹, P. D. Tall¹, C. B. Ndao¹, E. H. O. Gueye¹, M. B. Gaye¹, J. K. Dangbegnon², B. D. Ngom^1,, J. R. Botha², A. C. Beye¹

The influence of growth parameters on the structural, morphological and optical properties of Mg_xZn_1-xO grown on sapphire substrate by metal organic chemical vapor deposition is studied. Pure oxygen gas is used as oxidant, bis-methyl-cyclopentadienyl magnesium ((MeCp)₂Mg) and diethyl zinc are used as Mg and Zn source, respectively. The growth temperature between and 320°C and 620°C, the VI/II (O/Mg, Zn) ratio ranging from 60 to 960 and the growth rate from 0.5 to 3.3 m/h, are systematically varied to determine their effects upon the above mentioned physical properties. Structural, morphological and optical properties of the thin films are characterized by means of X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Photoluminescence (PL). Experimental results indicate that the growth conditions are essential for engineering the growth of Mg_xZn_1-xO. The optimum substrate temperature is found to be 420°C for the growth of Mg_xZn_1-xO with a solid composition x below 30%, composition above which a phase segregation has been previously observed. With increasing temperature, strong parasitic reaction between (MeCp)₂Mg and oxygen is found to occur before they rich the substrate.

MgZnO ternary alloys, MOCVD, bis-methyl-cyclopentadienyl magnesium ((MeCp)2Mg), Columnar growth