A NEW PREPARATION TECHNIQUE FOR YBA2CU3O7 BICRYSTAL JUNCTIONS

We have developed an Ar ion-beam-assisted technique for preparing YBa2 Cu3O7 (YBCO) bicrystal junctions with the apropos critical current, hi gh normal resistance and high characteristic voltage. The dependence o f the critical current and normal resistance of YBCO bicrystal junctio ns on the ion beam energy and annealing temperature has been investiga ted. By using this technique, junctions with normal resistance R-n up to 3-8 Omega and characteristic voltage IcRn of 200-720 mu V have been obtained. In addition, the scaling relation of the characteristic vol tage with the critical current has been examined, which is in good agr eement with the results obtained by other researchers. An infrared det ector was fabricated by the YBCO bicrystal junction with high normal r esistance of 6 Omega and characteristic voltage of 720 mu V. The obtai ned maximum responsitivity of the detector was up to 220 V/W at 77 K. Its noise equivalent power (NEP) at 78 K was of 9.0 x 10(-13) W/root H z. (C) 1997 Elsevier Science B.V.