An Extended Unified Schottky-Poole-Frenkel Theory to Explain the Current-Voltage Characteristics of Thin Film Metal-Insulator-Metal Capacitors with Examples for Various High-k Dielectric Materials

Historically, there is a controversy regarding the current-voltage (I-V) characteristics of thin film MIM (metal-insulator-metal) capacitors, which is quite frequently modeled by either the Schottky model or the Poole-Frenkel model. In this paper, the author points out that the two models actually can be unified. The physics underlying this model involves a non-uniform distribution of deep donor defect states such that a very large quantity of defect states exist at the two interface of the MIM capacitor while the density of defect states in the insulator bulk is relatively low, resulting in an M/n-i-n/M structure. This unified Schottky-Poole-Frenkel model can be further extended to include other effects like space charge limited current and tunneling. The effect of trap limited space charge limited current is also discussed. Examples of the application of this theory will be provided for MIM capacitors based on various high-k dielectric materials like tantalum oxide, titanium oxide, zirconium oxide and aluminum oxide. (C) 2012 The Electrochemical Society. All rights reserved.