This invention relates to an infrared detecting element and also an infrared imaging device.
Some infrared detectors use Si crystals and detect infrared rays having wavelengths equal to or longer than several micrometers. Such infrared detectors are of two types, the first type being produced by doping impurities into the Si crystals and the second type using heterojunction barriers.
Infrared Detectors II, Chapter 2, Semiconductors and Semimetals, written by P. R. Bratt, published from Academic Press in 1977, discloses the first-type infrared detectors.
Japanese published unexamined patent application 61-241985 discloses the second-type infrared detector. The documents "3P79" of the lecture in the thirty-third spring meeting of Applied Physical Society of Japan in 1986 also discloses the second-type infrared detector.
These two types of infrared detectors are useful for infrared two-dimensional imaging devices of a monolithic type. The first-type infrared detectors have the following drawback. Since the quantity of doped impurities is limited, the detector sensitivity is low and the detected wavelength is fixed in dependence on the type of the impurities. Accordingly, it is impossible to maximize the detector sensitivity at an arbitrary wavelength. The second-type infrared detectors are free from such a drawback.