Superconducting field effect transistors with YBa 2Cu 3O 7− x/SrTiO 3/YBa 2Cu 3O 7− x trilayer structure

Abstract

A new superconducting field effect transistor (SuFET) with symmetrical gate structure of YBa 2Cu 3O 7− x /SrTiO 3/YBa 2Cu 3O 7− x (YBCO/STO/YBCO) was fabricated by adopting both the contact structure of buried YBCO electrodes and buried isolation structure. The T c of the YBCO (100 nm)/STO (200 nm)/YBCO (5 nm) structures exceeded 50 K. The I– V characteristic of gate insulator STO was symmetric. The adoption of YBCO as electrode greatly improved T c values of ultrathin YBCO channels without buffer layers. We succeeded in SuFET operation with a YBCO channel of two-unit-cell thickness. The modulation factor exceeded 20%. The number of YBCO unit cell dependence on T c indicates that the degradation is negligible at the STO/YBCO interface.