Intersubband Transition in Si-based Quantum Wells and Application for Infrared Photodetectors

Intersubband transitions in quantum wells and superlattices have attracted a great deal of interest because of their potential applications in infrared detection and imaging. This is particularly important in Si-based heterostructures due to the advantage of monolithic integration with the conventional silicon signal processing electronics. In this paper, experimental observations of intersubband transition in SiGe/Si quantum wells and δ-doped layers in Si will be reviewed. In addition to intersubband transitions, two normal incident absorption processes; intervalence band transition and internal photoemission from two-dimensional hole gas in the quantum well will also be discussed. Finally, the progress in the application of SiGe/Si multiple quantum well structures for the fabrication of infrared detectors will be discussed.