Optical and electronic properties of carbon nitride

Since it was postulated in the mid-1980s, carbon nitride has seen most effort focussed on its mechanical properties because of its predicted hardness, unusual Poissonʹs ratio, etc. Far less work has been carried out on the optical and electronic characteristics. This paper gives a brief review of the current state of knowledge about them and tries to extract some generally applicable results from the span of those which have been reported. One of the main difficulties in this is the vast range of different compositions and structures, which can be produced, many of which give rise to conflicting conclusions about the effect of the nitrogen in the carbon matrix. An outline of the major effects on conductivity and optical gap is given and details of some of the proposed uses in the optoelectronics area are summarised.