Ion implantation effects on tunneling properties of Bi/sub 2/Sr/sub 2/Ca/sub 1/Cu/sub 2/O/sub 8+y/ intrinsic Josephson junctions

Abstract

We propose a feasible method to modify the tunneling properties of Bi 2 Sr 2 CaCu 2 O 8+ (Bi-2212) intrinsic Josephson junctions(IJJ's) using silicon ion implantation. The implantation is performed on 150 nm-height mesas at an acceleration voltage of 80 keV with doses ranging from 1 10 13 to 5 10 15 ions/cm 2 . The critical current of IJJ's rapidly decreases with increasing doses, while the critical temperature hardly changes. The small amount of Si impurities affect on the interlayer coupling but not the gap of the CuO 2 bilayers. The RF response of a Si-implanted IJJ is demonstrated and reveals clear Shapiro steps as the plasma frequency decreases. Index Terms-Bi 2 Sr 2 CaCu 2 O 8+ , high-Tc superconductors, intrinsic Josephson effect, ion implantation, shapiro step, tunneling.