Schottky-barrier diode radiant energy detector with extended longer wavelength response

In a radiation detector for operation at temperatures low enough to avoid excessive dark current including a region of semiconductive material relatively lightly doped in its bulk and a region of a conductive material, which have respective ohmic contacts thereto and share a surface therebetween at which a Schottky-barrier contact is made, arranged for operation in a hot carrier mode to provide photoemission of charge carriers responsive to radiation entering said region of semiconductive material, the improvement for extending longer wavelength spectral response of the photoemission process wherein the doping type of said semiconductive material is such as to make the Schottky-barrier potential at said Schottky-barrier contact less than half band gap voltage for that semiconductor material and wherein a layer of substantially higher doping concentration is formed in a portion of said region of semiconductive material immediately adjoining the surface at which said Schottky-barrier contact is made, which layer is of such thinness as to be substantially depleted of charge carriers during said operation and has a doping concentration chosen to lower the Schottky-barrier potential without undue increase in the dark current at the temperature of operation.