Abstract: An improved photoconductive sensor is provided which includes a substrate of calcium fluoride or barium fluoride in monocrystalline form upon which has been sputtered under controlled conditions a thin unannealed monocrystalline film having the formula Pb.sub.1-x Sn.sub.x Te where x = about 0-0.3. The conditions under which the film is deposited are controlled so that the film exhibits a cutoff wavelength between about 6.mu.m and about 15.mu.m, a photoconductive responsivity which may be as high as up to about 10.sup.3 V/watt at 77.degree. K and a detectivity peak value which may be as high as up to about 1.5 .times. 10.sup.10 cm-Hz.sup.1/2 /watt at frequencies above the 1/f noise frequency. The film also exhibits a fast response time of less than about 100 nanoseconds and is usually present in a thickness, for example about 1-2.mu.m, corresponding to high quantum efficiency and minimal contribution of unexcited film to detector noise.

Abstract: Photovoltaic diodes prepared by the methods of the invention include p-n (or n-p) heterojunction or homojunction diodes as well as Schottky barrier diodes where both elements of the diode comprise thin monocrystalline films of Pb.sub.1-x Sn.sub.x Te or a thin monocrystalline film of Pb.sub.1-x Sn.sub.x Te and an appropriate thin barrier metal film. Such a monocrystalline Pb.sub.1-x Sn.sub.x Te film is sputter deposited, has a composition Pb.sub.1-x Sn.sub.x Te which may range from x = 0.0 to about x = 0.3 and, consequently, can be preselected to have a photovoltaic response with response cutoff wavelengths ranging from about 6.0.mu.m to about 25.mu.m at 77.degree. K.