Book excerpt: Semiconductor Heterojunctions investigates various aspects of semiconductor heterojunctions. Topics covered include the theory of heterojunctions and their energy band profiles, electrical and optoelectronic properties, and methods of preparation. A number of heterojunction devices are also considered, from photovoltaic converters to photodiodes, transistors, and injection lasers. Comprised of eight chapters, this volume begins with an overview of the theory of heterojunctions and a discussion on abrupt isotype and anisotype heterojunctions, along with graded heterojunctions. The reader is then introduced to the energy band profiles of isotype and anisotype heterojunctions, the practical aspects of their fabrication and characterization, and their electronic and optoelectronic properties. Some methods used in the preparation of heterojunctions are also described, including the chemical method, solution growth method, alloying method, and sputtering method. The remaining chapters focus on the characterization of the grown layers, examples of heterojunction devices, and experimental work on heterojunctions. This monograph is intended for research workers and graduate students.