Capacitance-voltage analysis of LaAlO3/SrTiO3 heterostructures

Abstract

We performed capacitance-voltage analysis of 5-nm-thick LaAlO3/SrTiO3 heterostructure containing two-dimensional-electron-gas (2DEG) at the interface. The complex impedance of the heterostructure was measured as a function of frequency for a wide range of gate biases. The impedance spectra showed a different behavior above and below an applied voltage of -1.8V. The capacitance determined from the impedance was approximately 1.2 nF above -1.8V and was drastically reduced to similar to 0.01 nF below this voltage, owing to depletion of 2DEG and the insulating SrTiO3 underneath it. This suggests that devices utilizing LaAlO3/SrTiO3 can facilitate switching operations in a very small voltage range. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4798334]