SrTiO3/GdTiO3 heterostructure field effect transistors

We report on the first high electron density SrTiO₃/GdTiO₃ (STO/GTO) heterostructure field effect transistors (HFETs). Recently, there has been great interest in high density 2DEGs formed at the interfaces between perovskite oxides [1]. In particular, the STO/GTO interface has been shown to have a sheet charge density of 3 × 10¹⁴ cm^-2, equivalent to 0.5 e^- per unit cell [2], due to the polar discontinuity at the interface (Fig. 2) [3], which is the highest achieved sheet charge density for any semiconductor 2D electron gas (2DEG). The high charge density and the high breakdown strength of these systems make them promising for electronics and plasmonics, as well as for new applications of correlated electron gas systems [4]. In this work, we show for the first time, current modulation in the STO/GTO system, with channel charge modulation of 6×10¹³ electrons/cm², which is the highest reported value for any semiconductor material system.