Controlling the TiN electrode work function at the atomistic level: a first principles investigation

TL;DR

This study uses first principles simulations to analyze how nitrogen vacancies and surface oxidation affect the work function of TiN electrodes, providing insights for device optimization.

Contribution

It offers a detailed atomistic understanding of how defects and oxidation influence TiN work function, aiding in tailored electrode design.

Findings

Nitrogen vacancies lower the work function of TiN.

Surface oxidation increases the work function.

Surface orientation significantly affects defect impact.

Abstract

The paper reports on a theoretical description of work function of TiN, which is one of the most used materials for the realization of electrodes and gates in CMOS devices. Indeed, although the work function is a fundamental quantity in quantum mechanics and also in device physics, as it allows the understanding of band alignment at heterostructures and gap states formation at the metal/semiconductor interface, the role of defects and contaminants is rarely taken into account. Here, by using first principles simulations, we present an extensive study of the work function dependence on nitrogen vacancies and surface oxidation for different TiN surface orientations. The results complement and explain a number of existent experimental data, and provide a useful tool to tailoring transport properties of TiN electrodes in device simulations.