Ion implantation effects on tunneling properties of Bi2Sr2Ca1Cu2O8+y intrinsic Josephson junctions

We propose a feasible method to modify the tunneling properties of Bi₂Sr₂CaCu₂O_8+y (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 1×10¹³ to 5×10¹⁵ ions/cm². 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 CuO₂ bilayers. The RF response of a Si-implanted IJJ is demonstrated and reveals clear Shapiro steps as the plasma frequency decreases.