Infuence of Substrate Temperature on Stress and Morphology Characteristics of Co Doped ZnO Films Prepared by Laser-Molecular Beam Epitaxy

Zn1exCox O(x 0.05) thin films are deposited on sapphire(0001) substrates by laser-molecular beam epitaxy technique at different substrate temperatures. The structural, stress and morphology evolution features are investigated by means of X-ray diffraction and atomic force microscopy. The surface parameters of roughness exponent a, root mean square(RMS) roughness w and autocorrelation length x are calculated and the surface parameters are preliminarily analyzed. The values of a vary from 0.7 to 0.9. The RMS roughness w is less than 2.2 nm, and it increases with increasing T s from 300 to 400 C, and then decreases when T s is 500 C. The autocorrelation length x decreases monotonously with the increase in T s from 300 to 500 C, which indicates that the increase in T s restrains the spread of the surface fluctuations until T s is higher than 400 C.