Electrochemical doping of few layer ZrNCl from first-principles: electronic and structural properties in field-effect configuration

TL;DR

This paper presents a first-principles method for modeling electrochemical doping in field-effect devices, revealing that only one layer of ZrNCl is doped and inducing significant structural changes, challenging previous assumptions.

Contribution

The study introduces a novel first-principles approach to simulate doping in field-effect configurations, providing detailed insights into structural and electronic effects in ZrNCl.

Findings

Only one ZrNCl layer is electrochemically doped.

Doping induces large structural changes within the layer.

Density of states at the Fermi energy remains unchanged with doping.

Abstract

We develop a first-principles theoretical approach to doping in field-effect devices. The method allows for calculation of the electronic structure as well as complete structural relaxation in field-effect configuration using density-functional theory. We apply our approach to ionic-liquid-based field-effect doping of monolayer, bilayer, and trilayer ZrNCl and analyze in detail the structural changes induced by the electric field. We show that, contrary to what is assumed in previous experimental works, only one ZrNCl layer is electrochemically doped and that this induces large structural changes within the layer. Surprisingly, despite these structural and electronic changes, the density of states at the Fermi energy is independent of the doping. Our findings imply a substantial revision of the phase diagram of electrochemically doped ZrNCl and elucidate crucial differences with superconductivity in Li intercalated bulk ZrNCl.