Significant progress has occurred during the last few years in device technologies and these are surveyed in this new volume. Included are Si/(Si-Ge) heterojunctions for high-speed integrated circuits, Schottky-barrier arrays in Si and Si-Ge alloys for infrared imaging, III-V quantum-well detector structures operated in the heterodyne mode for high-data-rate communications, and III-V heterostructures and quantum-wells for infrared emissions.