Au-gated SrTiO_3 field-effect transistors with large electron concentration and current modulation

摘要

We report the fabrication of low-leakage rectifying Pt and Au Schottky diodes and Au-gated metal-semiconductor field effect transistors (MESFETs) on n-type SrTiO_3 thin films grown by hybrid molecular beam epitaxy. In agreement with previous studies, we find that compared to Pt, Au provides a higher Schottky barrier height with SrTiO_3. As a result of the large dielectric constant of SrTiO_3 and the large Schottky barrier height of Au, the Au-gated MESFETs are able to modulate ～1.6 × 10~(14)cm~(-2) electron density, the highest modulation yet achieved using metal gates in any material system. These MESFETs modulate current densities up to ～68 mA/mm, ～20× times larger than the best demonstrated SrTiO_3 MESFETs. We also discuss the roles of the interfacial layer, and the field-dependent dielectric constant of SrTiO_3 in increasing the pinch off voltage of the MESFET.