This book contains papers that were presented at the International Conference on Polycrystalline Semiconductors - Grain Boundaries, Dislocations and Het erointerfaces - (POLYSE '90), which was held in Schwabisch Hall, FRG, from July 30 to August 3, 1990. This conference was a satellite conference of the 20th International Conference on the Physics of Semiconductors. POLYSE '90, like its predecessor POLYSE '88, brought together scientists from research in stitutions and industrial laboratories with a view to bridging the gap between fundamental and technological aspects of polycrystalline...