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.