Preparation and characterization of CeO₂‐based superconducting field effect transistors

High‐T_c superconducting field effect transistors using CeO₂ as the dielectric layer in combination with ultrathin YBa₂Cu₃O_7−δ layers have been prepared and investigated. The preparation process of these devices is described in detail. CeO₂ is very compatible with ultrathin YBa₂Cu₃O_7−δ layers, resulting in T_c values consistent with SrTiO₃‐based superconducting field effect transistors. The dielectric constant and the breakdown field of the CeO₂ layer are reproducible in all investigated samples, yielding values for ε_r≊20 and E_bd≊2×10⁸ V/m. This results in a charge transfer of ΔN=±2 μC/cm². In the charge carrier enhancement mode this value is close to SrTiO₃‐based superconducting field effect transistors. So far, the maximum achieved modulation of the charge carrier density by the use of CeO₂ as dielectric is 1.5%.