Electrically programmable bistable capacitor for high-frequency applications based on charge storage at the (Ba,Sr)TiO 3/Al 2O 3 interface

Abstract

Hysteresis is induced in paraelectric (Ba,Sr)TiO 3 (BST) thin-film capacitors by inserting an Al 2O 3 barrier layer of a few nanometers in thickness between the BST layer and the electrode. The observed hysteresis is explained by ambipolar charge carrier injection through the Al 2O 3 layer and charge storage at the BST/Al 2O 3 interface. The magnitude of the hysteresis can be directly adjusted by manipulating the thickness ratio between BST and Al 2O 3. Taking into account the low loss of (Ba,Sr)TiO 3 capacitors, the observed switching and retention characteristics are suitable for application as non-volatile programmable high-frequency devices, e.g., in radio-frequency identification. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.