Voltage tunable two-color InAs∕GaAs quantum dot infrared photodetector

We report a bias voltage tunable two-color InAs∕GaAs quantum dot infrared photodetector working under the normal incidence infared irradiation. The two-color detection of our device is realized by combining a photovoltaic and a photoconductive response by bias voltage tuning. The photovoltaic response is attributed to the transition of electron from the ground state to a high continuum state. The photoconductive response arises from the transition of electron from the ground state to the wetting layer state through the barrier via Fowler–Nordheim tunneling evidenced by a broad feature of the photocurrent peak on the high energy side.