Nano-oxidation of superconducting flux flow transistor using a conductive atomic force microscope tip



The atomic force microscopy (AFM) has exhibited its capability to fabricate the nano-scale electronic devices. We have fabricated superconducting flux flow transistors (SFFTs) in thin superconducting films by localized anodization using an AFM lithography method. The SFFT is composed of two strips, which is characterized as a transresistance device: one strip is as a source and drain terminal, the other is as a gate terminal. Generally, the channels of SFFT have been fabricated by chemical wet etching method and dry etching method. In this study we present a new fabrication of the SFFT with single or two channels using the artificial pattern formation method based on the AFM lithography. The critical current density in the fabricated SFFT with a multi-channel structure was decreased applying the current in the gate current line. From the measured results, it is shown that the critical current of an SFFT with two channels is larger than the critical current of single-channel due to the magnetic coupling between channels. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)