Electrically induced colossal capacitance enhancement in LaAlO3/SrTiO3 heterostructures

The demonstration of a tunable conductivity for the LaAlO3/SrTiO3 interfaces by field effect drew significant attention to the development of oxide-based electronics. The increase in the gate capacitance of the LaAlO3/SrTiO3-based field-effect transistor is particularly important for conductivity modulation and the development of logic devices. Here, we demonstrate the annihilation of quantum capacitance and colossal capacitance enhancement (approximately 1000%) in LaAlO3/SrTiO3 heterostructures by DC gate voltage at room temperature, which we attribute to the motion of oxygen vacancies through the thickness of the LaAlO3 layer. These capacitor devices will provide a platform for the further development and application of metal-oxide-semiconductor transistors. Demonstration of a tunable conductivity of the LaAlO3/SrTiO3 interfaces by field effect drew significant attention to the development oxide-based electronics. Increase in the gate capacitance of LaAlO3/SrTiO3-based field-effect transistor is particularly important to the conductivity modulation and the development of logic device. Here, we demonstrate that annihilation of quantum capacitance and colossal capacitance enhancement (about 1000%) in the LaAlO3/SrTiO3 heterostructures by DC gate voltage at room temperature, which we attribute to the motion of oxygen vacancies through the LaAlO3 layer thickness. The capacitor devices would provide a platform for the further development and application of metal-oxide-semiconductor transistor devices. Shuxiang Wu, Shuwei Li and co-workers from Sun Yat-sen University in China have significantly enhanced capacitance in a heterostructure that features two insulating oxides—lanthanum aluminate oxide (LAO) and strontium titanate oxide (STO). The interface between LAO and STO is known to be conductive under certain conditions, owing to the formation of a high-mobility ‘two-dimensional electron gas’ in which electrons are free to move in two directions. The researchers determined the effect of a direct current bias on a capacitor device comprising the LAO/STO interface. They found that the capacitance undergoes a reversible switching when subjected to voltage pulses with opposite polarities and, at low switching frequencies, is enhanced by approximately 1000% at room temperature. This effect — which holds promise for field-effect devices — may arise from the reversible redistribution of oxygen vacancies throughout the LAO layer.