Abstract: A semiconducting photodiode for detecting light at a predetermined wavelength includes a first semiconducing region having a first conductivity type which is a quaternary alloy of Hg, Mn, Cd, and Te. A second semiconducting region having a second conductivity type electrically contacts the first semiconducting region, such that a semiconducting junction is formed between the first and second regions. The relative proportions of Hg, Mn, and Cd in the first region are selected so that the bandgap energy of the first region is approximately equal to the spin orbit splitting energy of the first region at the desired wavelength.

Abstract: A low-leakage, heterojunction photodiode for use as a detector sensitive to infrared radiation is provided. The diode structure comprises a PbTe substrate of n-type conductivity with an n-type epitaxial buffer layer on the substrate and an epitaxial active layer on the buffer layer. The buffer layer is either Pb.sub.(1-x) S.sub.x Te or Pb.sub.1-x Se.sub.x Te with the atomic fraction of S or Se, x, being greater than 0 but less than 0.1. The active layer is Pb.sub.1-y Sn.sub.y Te with the atomic fraction of Sn, y, being greater than 0 but less than 0.3. There is a p-n junction created in the active layer with the n side of the junction being adjacent the buffer layer. Metal is deposited on the substrate and on the active layer to provide electrical contact to the diode.

Abstract: A method of making a junction in semiconductive materials to improve the spectral response of the junction in photovoltaic detectors. A first layer of semiconductive material is grown, by epitaxy technique, on a substrate of semiconductive material of the same conductivity type. Growth of the first layer is discontinued and the temperature is changed. Then a second layer of opposite conductivity type is grown on the first layer.