The impact of nitrogen doping on the linear and nonlinear terahertz response of graphene

TL;DR

This paper investigates how nitrogen doping affects the linear and nonlinear terahertz responses of graphene, revealing that substitutional doping significantly enhances mobility and nonlinear effects compared to adsorbed nitrogen.

Contribution

It provides a detailed computational analysis of how different nitrogen doping methods alter graphene's electronic and terahertz response properties.

Findings

Substitutional nitrogen doping makes conduction bands more parabolic.

Substitutional doping has a greater impact on terahertz mobility.

Nitrogen doping influences third harmonic generation in graphene.

Abstract

It is well known that impurities play a central role in the linear and nonlinear response of graphene at optical and terahertz frequencies. In this work, we calculate the bands and intraband dipole connection elements for nitrogen-doped monolayer graphene using a density functional tight binding approach. Employing these results, we calculate the linear and nonlinear response of the doped graphene to terahertz pulses using a density-matrix approach in the length gauge. We present the results for the linear and nonlinear mobility as well as third harmonic generation in graphene for adsorbed and substitutional nitrogen doping for a variety of doping densities. We show that the conduction bands are more parabolic in graphene structures with substitutional nitrogen doping than for those with adsorbed nitrogen. As a result, substitutional doping has a greater impact on the terahertz mobility and nonlinear response of graphene than adsorbed nitrogen does.