Abstract: An infrared photodetector structure with voltage-tunable and -switchable photoresponses constructed of superlattices and blocking barriers. The photoresponses of the double-superlattice structure are also insensitive to the operating temperature changes. By using GaAs/AlxGa1-xAs system, the feasibility of this idea is verified. In the embodiment, the photoresponses can be switched between 6˜8.5 and 7.5˜12 m by the bias polarity and are also tunable by the bias magnitude in each detection wavelength range. In addition, the photoresponses are insensitive to operating temperatures ranging from 20 to 80 K. For the SLIP with few periods, the responsivity may be higher than the one with many periods and the operational temperature is higher. These results show the invention can be useful in the design of multicolor imaging systems.

Abstract: A superlattice infrared photodetector is disclosed, which can be fabricated easily by molecular beam epitaxy, has low power consumption and small dark current. Furthermore, the working temperature to operate the detector under background limited performance can be achieved by cooling down to the liquid nitrogen temperature. That is, the front and rear sides of the superlattice structure are added with blocking layers with sufficient height and width. The thickness is about 50 nm and the height of the energy barrier must be higher than the bottom of the second miniband of the superlattice structure by a value of more than 10 meV. Thereby, with the generation of photocurrent, the dark current is reduced at the same time. Therefore, the ratio of the photocurrent to the dark current can be improved effectively so that the working temperature for the background limited performance is increased vastly to even higher than 77 K.