Electrical Behaviour of Langmuir Films: A Review, Part II

Abstract

The electrical behaviour of thin films obtained by a variety of processes, e.g. thermal evaporation in vacuum, has been extensively studied. The study of organic mono- and multilayer films obtained by the Blodgett–Langmuir technique (commonly referred to as Langmuir films), however, has gained considerable momentum only during the past decades. Unlike evaporated films, the stiking features of these organic films are their controllable thicknesses down to one monolayer (~25 Å) and the possibility of obtaining them free from holes and conducting imperfections. The aim of this paper is to describe the film deposition techniques, some of the properties of the films so obtained and to review their electrical behaviour. It is also intended to make this review a comprehensive and up-to-date source of information for those who are either already engaged in this field or are planning to adopt Langmuir films for future investigations.In this survey, emphasis is put on the possible problems worth further study to get more insight into the basic properties of these films. Further, since the latter possess some interesting electrical properties, this paper may prove useful in the assessment of our depth of knowledge about them and in reducing the existing gap between basic research and technological applications. Their potential usefulness in developing devices is therefore also discussed.The survey has been divided into two parts. Part I was concerned with deposition techniques, the physical properties of Langmuir films and certain electrical properties, namely dielectric behaviour and electrical conduction phenomena. This second part is concerned with electrical breakdown behaviour, voltage induced changes in electrical behaviour (forming) and ionic transport phenomena in the films and finishes, with suggestions as to future trends in work with such films together with a summary of possible applications.To assist the reader, the two parts have been numbered consecutively with regard to sections of the text, figures and references. “Appropriate” references already cited in Part I are given again at the end of this part.