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The superconductor-semiconductor contact diode, or super-Schottky-barrier-diode, has been examined theoretically and experimentally as a video detector of high-frequency radiation. The measured noise-equivalent power (NEP) of the device is believed to be the smallest value ever reported in the literature for video detection. Moreover, the high reliability established for the ordinary Schottky barrier diode is in evidence for the proposed diode. The doping of the semiconductor is chosen large enough so that electron tunneling dominates the volt-ampere behavior of the diode. As such, for T < Tc and V < Δ, the diode exhibits a high degree of nonlinearity in its volt-ampere characteristic. It is this nonlinearity that the super-Schottky-diode exploits. Initial results with p-type GaAs at 1 °K have yielded an NEP of 2 × 10−15 W/Hz1/2 at 10 GHz.

The short-circuit current of both diffused and n-type metal semiconductor junctions during 2-MeV electron irradiation was measured. The results indicate that electron diffusion length in the Zn-diffused p-type region is proportional to the reciprocal of the square root of the donor concentration. The electron-diffusion length ranges from 20 μ for lightly doped diodes to 2 μ for heavily doped diodes. The hole-diffusion lengths are less than 1.0 μ in heavily doped surface barrier diodes. The thickness of the active radiative recombination region for diffused diodes under forward bias was measured and compared with the short-circuit current results. These results suggest that the pre-irradiation electron lifetime is ≈ (10−9 ND)−1, where ND is the substrate donor concentration. This behavior is consistent with radiative recombination between donors and free holes.

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