We report a two-color quantum dot infrared photodetector (QDIP) using double tunneling barriers (DTBs) on one side of the InGaAs/AlGaAs dots. The two-color detection is achieved by changing the polarity of the applied bias voltages. In contrast, the same QDIP structure without the DTBs does not exhibit this detection wavelength tunability by switching the bias polarity. The two-color detection is ascribed to a different escape mechanism of electrons between positive and negative biases. The electrons escape out of the quantum well through resonant tunneling for a positive bias voltage while tunnel through a triangular barrier for a negative bias voltage.
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Huang et al. (2011) studied this question.
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