The incidence of symmetric tilt grain boundaries in polycrystalline thin films of gold

Abstract

Polycrystalline thin films have attracted increased research attention in recent times, due to their importance in semiconductor, magnetic, magneto-optic and other applications. These films are often found to exhibit a strong fiber texture with one of the low index directions, , , perpendicular to the film plane. The grain boundaries in such polycrystalline films are usually perpendicular to the film surface implying a tilt character, i.e., the rotation axis is parallel to the grain boundary plane, and also parallel to the common film normal. According to Neumann`s principle, a symmetric boundary should represent an extremum -- either a minimum or a maximum -- of the interfacial energy with respect to changes of boundary plane, and Wolf has shown by computer simulation that symmetric tilt boundaries often correspond to energy minima. If symmetric tilt boundaries generally have lower energy than other boundaries, one might expect a larger than random proportion of all the boundaries to be of this type. In this paper, the authors report a preliminary determination of the proportion of grain boundaries (in the immediate vicinity of triple junctions) that have a symmetric tilt character in polycrystalline gold thin films, prepared by thermal evaporation and subsequent annealing.