Isotropic or anisotropic screening in black phosphorous: can doping tip the balance?

TL;DR

This study uses first-principles calculations to explore how doping influences charge screening in black phosphorus, revealing that doping can significantly alter the material's anisotropic or isotropic screening behavior.

Contribution

It demonstrates that doping can tip the balance between isotropic and anisotropic screening in black phosphorus, a novel insight into its electronic properties.

Findings

Doping increases charge screening in BP.

Doping significantly changes dielectric tensor elements.

Doping can switch screening from anisotropic to isotropic.

Abstract

Black phosphorus (BP), a layered van der Waals (vdW) crystal, has unique in-plane band anisotropy and many resulting anisotropy properties such as the effective mass, electron mobility, optical absorption, thermal conductivity and plasmonic dispersion. However, whether anisotropic or isotropic charge screening exist in BP remains a controversial issue. Based on first-principles calculations, we study the screening properties in both of single-layer and bulk BP, especially concerning the role of doping. Without charge doping, the single-layer and bulk-phase BP show slight anisotropic screening. Electron and hole doping can increase the charge screening of BP and significantly change the relative static dielectric tensor elements along two different in-plane directions. We further study the charge density change induced by potassium (K) adatom near the BP surface, under different levels of charge doping. The calculated two-dimensional (2D) charge redistribution patterns also confirm that doping can greatly affect the screening feature and tip the balance between isotropic and anisotropic screening. We corroborate that screening in BP exhibit slight intrinsic anisotropy and doping has significant influence on its screening property.