Charge transport in the normal state of electron- or hole-doped YBa₂Cu₃O_7-x

By using a field-effect transistor configuration, we have demonstrated that it is possible to dope electrons or holes into an initially underdoped YBa2Cu3O7-x film at room temperature. The results of systematic measurements of the dual-type transconductance indicate comparable field-effect mobilities for electrons and holes. We propose a model based on band bending and localized electronic states within the band gap of the Mort insulator to explain the dual-type charge transport.