Experimental proof of the electronic charge-transfer mechanism in a YBa₂Cu₃O_7-x-based field-effect transistor

The dynamics of charge transfer in a YBa₂Cu₃O_7-x-based field-effect transistor were studied in the normal state using signal shape analysis and frequency mixing techniques, the latter being the most sensitive means of measuring field effect utilized so far. The speed of response was found to be limited only by the RC time constant of the device configuration (∼9 μsec). Also the electric field modulation of the channel resistance was unchanged from dc to the highest frequency achieved in this device, showing the absence of any significant "slow" component. This observation unambiguously demonstrates that direct field induced modulation of the charge carrier density plays a major role in the relatively fast electric field effect in metal-oxide superconductors.