A reissue of a classic Oxford text. The book sets out theoretical concepts and makes comparisons with experiments for a wide variety of phenomena in non-crystalline materials.

This second edition deals in an elementary way with electrons in non-crystalline systems. It reflects advances in the theory of interactions in non-crystalline systems, provides a more detailed discussion of the "minimum metallic conductivity", and addresses the relevance of disorder in the new high-temperature semiconductors.

The Workshop on Physics and Application of Non-crystalline Semiconductors in Optoelectronics was held from 15 to 17 October 1996 in Chisinau. republic of Moldova and was devoted to the problems of non-crystalline semiconducting materials. The reports covered two mjlin topics: theoretical basis of physics of non -crystalline materials and experimental results. In the framework of these major topics there were treated many subjects. concerning the physics of non-crystalline semiconductors and their specific application: -optical properties of non-crystalline semiconductors; -doping of glassy semiconductors and photoinduced effects in chalcogenide glasses and their application for practical purposes; -methods for investigation of the structure in non-crystalline semiconductors -new glassy materials for IR trasmittance and optoelectronics. Reports and communications were presented on various aspects of the theory. new physical principles. studies of the atomic structure. search and development of optoelectronics devices. Special attention was paid to the actual subject of photoinduced transformations and its applications. Experimental investigations covered a rather wide spectrum of materials and physical phenomena. As a novel item it is worth to mention the study of nonlinear optical effects in amorphous semiconducting films. The third order optical non linearities. fast photoinduced optical absorption and refraction. acusto-optic effects recently discovered in non-crystalline semiconductors could potentially be utilised for optical signal processing. The important problems of photoinduced structural transformations and related phenomena. which are very attractive and actual both from the scientific and practical points of view. received much attention in discussions at the conference.