ZnO nanostructures were fabricated by a hydrothermal decomposition method of mixing appropriate quantities of ammonia（25%） and zinc chloride solution.The influences of the chemical reactions

the depth-dependent growth and different substrates with horizontal or vertical setting on ZnO nanostructures were compared in our experiment.The structures and morphologies of ZnO samples were investigated by XRD and SEM.Compared with Si substrates

the Cu substrates are better for the growth of good aligned ZnO nanorods with the wurtzite structure.The growth mechanism of ZnO nanorods by the hydrothermal decomposition method was suggested according to the influences of the ammonia pressure on the growth of vertically aligned ZnO nanorods.