title: Very large capacitance enhancement in a two-dimensional electron system.
abstract: Increases in the gate capacitance of field-effect transistor structures allow the production of lower-power devices that are compatible with higher clock rates, driving the race for developing high-κ dielectrics. However, many-body effects in an electronic system can also enhance capacitance. Onto the electron system that forms at the LaAlO(3)/SrTiO(3) interface, we fabricated top-gate electrodes that can fully deplete the interface of all mobile electrons. Near depletion, we found a greater than 40% enhancement of the gate capacitance. Using an electric-field penetration measurement method, we show that this capacitance originates from a negative compressibility of the interface electron system. Capacitance enhancement exists at room temperature and arises at low electron densities, in which disorder is strong and the in-plane conductance is much smaller than the quantum conductance.
authors.affiliation: Department of Physics, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA.
authors.forename: Lu
authors.initials: L
authors.lastname: Li
authors.forename: C
authors.initials: C
authors.lastname: Richter
authors.forename: S
authors.initials: S
authors.lastname: Paetel
authors.forename: T
authors.initials: T
authors.lastname: Kopp
authors.forename: J
authors.initials: J
authors.lastname: Mannhart
authors.forename: R C
authors.initials: RC
authors.lastname: Ashoori