Grain boundaries in polycrystalline thin films of undoped material were shown to act as efficient H traps rather than as easy paths for diffusion. A comparison of H diffusion in polycrystalline and monocrystalline material demonstrated that diffusion in the former was appreciably suppressed as compared to the latter. It was concluded that these results had important implications with regard to the hydrogenation of thin polycrystalline films.

W.B.Jackson, N.M.Johnson, C.C.Tsai, I.W.Wu, A.Chiang, D.Smith: Applied Physics Letters, 1992, 61[14], 1670-2