Effect of defect structure on the electrical conduction mechanism in metallic thin films

Abstract

Thin metal films can be deposited in a number of different ways. As a result several types of defects or impurities are frozen in the film. In most practical cases films exhibit grain boundaries which play a decisive role in transport properties. This paper reviews the advances that have been made during the last five years in the field of theoretical description of electronic scattering at grain boundaries. Analytical expressions for the transport parameters (such as resistivity, temperature coefficient of resistivity and thermopower) of columnar, monocrystalline and polycrystalline films are derived. Care has been taken to give linearized equations for the transport phenomena. Methods for extracting grain parameters are outlined. Special attention is focused on correlated size effects. Imperfection or impurity effects on the film resistivity and thermopower are considered. Methods for determining the energetic parametersU andV and the componentS 1 of the thermopower associated with imperfections are proposed. Special emphasis is placed on procedures for identifying imperfections by simultaneous study of the restructuration processes induced by thermal ageing and of the changes in transport parameters on ageing.