A SIMS study on Mg diffusion in Zn0.94Mg0.06O/ZnO heterostructures grown by metal organic chemical vapor deposition

Zn0.94Mg0.06O/ZnO heterostructures have been grown on 2 in. sapphire wafer using metal organic chemical vapor deposition (MOCVD). Photoluminescence (PL) mapping demonstrates that Mg distribution on the entire wafer is very uniform (standard deviation of Mg concentration/mean Mg concentration = 1.38%) with average concentration of ∼6%. The effect of annealing on the Mg diffusion in Zn0.94Mg0.06O/ZnO heterostructures has been investigated in detail by using secondary ion mass spectrometry (SIMS). All the Mg SIMS depth profiles have been fitted by three Gaussian distribution functions. The Mg diffusion coefficient in the as-grown Zn0.94Mg0.06O layer deposited at 700 °C is two orders of magnitude lower than that of annealed samples, which clearly indicates that the deposition temperature of 700 °C is much more beneficial to grow ZnMgO/ZnO heterostructures and quantum wells.

► Mg diffusion coefficient in Zn0.94Mg0.06O was investigated by SIMS. ► A thick ZnO buffer layer is needed to reduce n-type background doping. ► 700 °C is the optimized temperature to grow ZnMgO/ZnO structures.