The a-axis oriented ZnO thin films were deposited onto sapphire substrates by pulsed laser deposition and were used to investigate the effects of pre-annealing upon O diffusion. The diffusion coefficient decreased, and the oxygen concentration in the tail regions of the profiles was reduced. Ion images of an oxygen tracer revealed high-diffusivity paths for oxygen tracer diffusion. The oxygen tracer diffusion in as-deposited and pre-annealed thin films were described by:

D(cm2/s) = 9.2 x 102 exp[-405(kJ/mol)/RT]

and

D(cm2/s) = 1.8 x 103 exp[-418(kJ/mol)/RT]

respectively.

I.Sakaguchi, K.Watanabe, Y.Adachi, T.Ohgaki, S.Hishita, N.Ohashi, H.Haneda: Key Engineering Materials, 2013, 566, 266-70