Construction of Band Profiles for Semiconductor Heterojunctions and Layered Structures

ABSTRACTBand profiles specify the position of all band edges as a function of distance from a sample surface or interface. They largely determine the electrical and optoelectronic properties of semiconductor heterostructures. Neither theory nor standard transport measurements alone have been able to give reliable values for band offsets, much less entire band profiles. However, the use of electroreflectance, which reveals crossover transitions between localized states or band edges present on opposite sides of an interface, and which allows us to measure accurately built-in fields, has allowed us to determine accurate band profiles for several types of semiconductor heterostructures. The procedure used to find the band profile is elucidated in detail for two technologically important cases.