Summary and Outlook

Abstract

In this book we have described the optical properties of semiconductors with a multi-valley band structure. GaAs, Al _x Ga_1−x As and related heterostructures are well suited as model systems for such semiconductors, because the band-gap energies and the constellation of various conduction-band minima can be tuned over a wide range. The character of the fundamental gap can even be changed from direct to indirect, both in reciprocal and in real space. This flexibility of the band structure allows one to systematically study the impact of a multi-valley scenario on the carrier dynamics as well as the modifications of the band structure due to the presence of carriers that are distributed among several valleys. This information is essential for the design of modern ultrafast electronic and optical devices.