Improved Transresistance Characteristics of Inductance-gate Type SFFT Using AFM Lithography

An atomic force microscope (AFM) was used to locally anodize the serial channels of an inductance-gate type superconducting flux flow transistor (SFFT) as narrow slits with a width of 50 mu m, a space of 25 mu m, and 12 turns, to improve the transresistance value. Among the serial channels that were anodized with the scanning tip of the AFM in the drain current line, channels 1 and 2 were 7.3 and 7.9 mu m wide, and 531 and 461 nm high, respectively. The critical current density in the serial channel of the fabricated SFFT, which was determined using an AFM modification method, was decreased by increasing the gate current. The measured current-voltage curves were compared with the simulated ones. The maximum transresistance value was 0.56 Omega at the drain current of 20 mA when the gate current was 6 mA. The transresistance characteristics of the inductance-gate type SFFT could be more improved than that of the single-channel type SFFT using an inductively coupled plasma lithography method