Electronic Properties of Amorphous Materials: Changes are considered which occur when the long-range order typical for crystals disappears.

A possible approach to the understanding of electronic properties of amorphous materials is to compare them with the corresponding crystalline materials, whose properties have been well explained. This approach has been exploited in the simple case of amorphous germanium, and I have indicated how the observed optical properties can be used to obtain information on the changes of electronic states, and what complications arise when we try to understand the transport properties.