Modulation of over 1014 cm−2 electrons in SrTiO3/GdTiO3 heterostructures

We demonstrate charge modulation of over 1014 cm−2 electrons in a two-dimensional electron gas formed in SrTiO3/GdTiO3 inverted heterostructure field-effect transistors. Increased charge modulation was achieved by reducing the effect of interfacial region capacitances through thick SrTiO3 cap layers. Transport and device characteristics of the heterostructure field-effect transistors were found to match a long channel field effect transistor model. SrTiO3 impurity doped metal–semiconductor field effect transistors were also demonstrated with excellent pinch-off and current density exceeding prior reports. The work reported here provides a path towards oxide-based electronics with extreme charge modulation exceeding 1014 cm−2.