Abstract
This commentary notes give brief discussion on material properties of high temperature superconductors from the aspect of suitability to the field effect device application and on principle concerning the modulation of superconductivity. Some examples of the drain current modulation in the test devices, YBCO-MISFETs, are shown. However, the actual data taken from the MISFETs are far from the goal. The major cause for this is arising from the degraded interface between YBCO channel layer and gate insulator. First measurement of the interfacial diffusion was carried out and some favorable combination of the gate insulator and YBCO channel is proposed.
