A super-Schottky contact diode made of Nb on heavily doped p-GaAs has been fabricated by electron-beam deposition under high vacuum, resulting in a rugged device having very reliable characteristics with detector current sensitivity S ≃ 1500 V-1and estimated NEP ≃ 1.2 × 10-15W/√HZ at 4.2 K under the optimum bias conditions.