Electric field effect of SrTiO/sub 3//YBa/sub 2/Cu/sub 3/O/sub 7-x/ bi-layer grown by MBE and PLD

Oxygen content and interface properties in SrTiO/sub 3//YBa/sub 2/Cu/sub 3/O/sub 7-x/(STO/YBCO) bi-layer definitely affect electric properties of superconducting field effect transistor (SuFET). Good interface can be obtained by molecular beam epitaxy (MBE). Deposition pressure of MBE is too low to oxygenate the ultra-thin YBCO through STO. The oxygen pressure of pulsed laser deposition (PLD) is high enough to oxygenate the YBCO but YBCO film surface is degraded by impurity gases because of its high oxygen pressure. We successfully combined MBE and PLD methods to obtain STO/YBCO bilayers with both good interface and electrical properties. The transconductance of SuFET was 5mS/cm, which is higher than SuFET grown by all-MBE and all-PLD.