Abstract
The author presents a detailed study of a wide variety of quantum well infrared photodetectors, which were chosen to have large differences in their optical and transport properties. Intersubband transitions based on photoexcitation from bound-to-bound, bound-to-quasicontinuum and bound-to-continuum quantum well states were investigated. The measurements and theoretical analysis included optical absorption, responsivity, dark current, current noise, optical gain, hot-carrier mean free path, net quantum efficiency, quantum well escape probability, quantum well escape time, as well as detectivity.