First-principles study of metal-induced gap states in metal/oxide interfaces and their relation with the complex band structure

TL;DR

This paper presents a simple model to predict the decay of metal-induced gap states in metal/insulator interfaces using bulk complex band structures, aligning well with detailed first-principles simulations and aiding material screening.

Contribution

A new simplified model that calculates energy-dependent decay factors of gap states based on bulk properties, reducing reliance on complex interface simulations.

Findings

Model agrees well with first-principles simulations

Influence of electrodes and polarization analyzed

Simplifies screening of materials for tunneling devices

Abstract

We develop a simple model to compute the energy-dependent decay factors of metal-induced gap states in metal/insulator interfaces considering the collective behaviour of all the bulk complex bands in the gap of the insulator. The agreement between the penetration length obtained from the model (considering only bulk properties) and full first-principles simulations of the interface (including explicitly the interfaces) is good. The influence of the electrodes and the polarization of the insulator is analyzed. The method simplifies the process of screening materials to be used in Schootky barriers or in the design of giant tunneling electroresistance and magnetoresistance devices.