Effect of Schottky barrier height lowering on resistance degradation of Fe-doped SrTiO3 thin-film capacitor

Feng Xue

doi:10.1063/5.0038873

Abstract

It is generally believed that the resistance degradation behavior of bulk and thin-film oxide capacitors arises from the oxygen vacancy migration within the oxide and/or the charge injection at the oxide/electrode interface. The magnitude of the degradation in the resistance has been theoretically studied in the literature by solving the electrochemical transport equations while assuming constant Schottky barrier height. The treatment of constant Schottky barrier height in existing models has led to significant underestimation of the resistance degradation. In this work, I incorporated the dependence of Schottky barrier height on the oxygen vacancy concentration at the interface into the existing model to simulate the degradation process in thin-film oxide capacitors. With the consideration of Schottky barrier height lowering from the interface dipole arising from the accumulation of oxygen vacancies at the cathode interface, I found that the leakage current can be increased by more than one order of magnitude, which is more consistent with experimental observations in comparison to the prediction from existing models.

Highlights

When SrTiO3 and/or its counterpart BaTiO3 are used in dielectric capacitors, the resistance degradation behavior is always an interesting topic because it is related to the lifetime of the capacitor
Different metallic electrodes can obviously determine the value of leakage current,39 we found that they do not affect the degradation time in my simulation
The barrier height lowering effect is considered by introducing interface dipole at the cathode/dielectric interface, which cannot be neglected as oxygen vacancies migrate toward and accumulate at the cathode under a bias voltage

Summary

Introduction

Strontium titanite (SrTiO3) has been used as a model system by researchers to explore the application of dielectric oxides in various electronic devices such as sensors,1 capacitors,2–7 and nonvolatile resistive random access memories.8–11 When SrTiO3 and/or its counterpart BaTiO3 are used in dielectric capacitors, the resistance degradation behavior is always an interesting topic because it is related to the lifetime of the capacitor. With oxygen vacancy migration during the degradation process, the surface state and the Schottky barrier height at the oxide/metal interfaces will be changing.

Results

Conclusion