Effects of doping and bias voltage on the screening in AAA-stacked trilayer graphene

TL;DR

This paper investigates how doping and bias voltage influence the screening behavior in AAA-stacked trilayer graphene, revealing tunable dielectric properties and complex screening regimes depending on doping levels and bias.

Contribution

It provides a comprehensive analysis of the static polarization and screening in AAA-stacked TLG, including effects of bias voltage and doping, with new insights into the tunability of its dielectric properties.

Findings

Screening properties depend on doping level and bias voltage.

Bias voltage effects can be modeled as a renormalization of interlayer hopping.

Screening behavior transitions from combined to graphene-like as doping increases.

Abstract

We calculate the static polarization of AAA-stacked trilayer graphene (TLG) and study its screening properties within the random phase approximation (RPA) in all undoped, doped and biased regimes. We find that the static polarization of undoped AAA-stacked TLG is a combination of the doped and undoped single layer graphene static polarization. This leads to an enhancement of the dielectric background constant along a Thomas-Fermi screening with the Thomas-Fermi wave vector which is independent of carrier concentrations and a 1/r^3 power law decay for the long-distance behavior of the screened coulomb potential. We show that effects of a bias voltage can be taken into account by a renormalization of the interlayer hopping energy to a new bias-voltage-dependent value, indicating screening properties of biased AAA-stacked TLG can be tuned electrically. We also find that screening properties of doped AAA-stacked TLG, when $\mu$ exceeds $\sqrt{2}\gamma$, are similar to that of doped SLG only depending on doping. While for $\mu<\sqrt{2}\gamma$, its screening properties are a combination of SLG and AA-stacked screening properties and they are determined by doping and the interlayer hopping energy.