Polycrystalline thin films were prepared by means of radio-frequency magnetron sputtering, and twin structures in the films were investigated by using transmission electron microscopy. It was found that (111) twin boundaries were present in films with thicknesses of 210 or 1000nm. Not only single twin boundaries, but also very narrow (111) twin lamellae (1nm) were observed in films of either thickness. It was suggested that the twin lamellae were stable even though the interfacial energy appeared to be much higher than that of single twin boundaries. It was also noted that there was a correlation between the width of the twin lamella, and the grain size.

J.W.Jang, Y.H.Kim, T.S.Hahn, S.S.Choi, S.J.Chung: Japanese Journal of Applied Physics, 1996, 35[2-6A], L699-702