Infrared quantum-dot detectors with diffusion-limited capture

Employing Monte-Carlo simulations we investigate parameters and optimize geometry of IR quantum-dot detectors with diffusion-limited capture into the dots surrounded by potential barriers. Our results show that structures with modulation doping of interdot matrix provide an effective separation of the localized and conducting electron states. In these structures, the capture time is mainly determined by the quantum dot concentration and the height of potential barriers around dots. The capture is not sensitive to the dot positions. It also weakly depends on the electric field up to the characteristic value, at which significant electron heating allows hot electrons to overcome the barriers. Optimizing the carrier capture and transit times, we show that quantum-dot structures have a lot of potentials for increasing the photoconductive gain and for the development of IR room-temperature detectors.