Resonant tunneling quantum dot infrared photodetector (RT-QDIP): separating dark current and photocurrent

In this paper, we present a novel approach to reduce dark current in quantum dot infrared photodetectors that uses resonant tunneling barriers to selectively block dark current while transmitting photocurrent. In such a device, carriers in the quantum dots (QD) are resonantly excited by an IR photon and they tunnel through a double AlGaAs barrier to be collected as photocurrent. This double barrier, which acts as a resonant tunneling filter, is located between adjacent QD layers. When the double AlGaAs barrier thickness and position are properly designed, the electron tunneling probability is /spl sim/1 at a particular energy, corresponding to the desired peak detection wavelength. At the same time, the tunneling probability is several orders of magnitude lower for energies that are tens of meV removed from the peak energy. Thus, the dark current which results from electrons with a broad energy distribution, will be significantly reduced by the resonant tunneling filter.