Carbon Kagome lattice and orbital frustration-induced metal-insulator transition for optoelectronics

TL;DR

This paper proposes a stable 3D carbon Kagome lattice that exhibits a metal-insulator transition driven by orbital frustration, with potential applications in optoelectronics due to its unique electronic and optical properties.

Contribution

It introduces a novel stable carbon Kagome lattice structure and explores its electronic properties, revealing a metal-insulator transition influenced by orbital frustration.

Findings

Stable carbon Kagome lattice with comparable stability to C60

Metal-insulator transition from graphene-like to direct-gap semiconductor

Optical properties similar to GaN and ZnO, with small effective masses

Abstract

A three-dimensional elemental carbon Kagome lattice (CKL), made of only fourfold coordinated carbon atoms, is proposed based on first-principles calculations. Despite the existence of 60{\deg} bond angles in the triangle rings, widely perceived to be energetically unfavorable, the CKL is found to display exceptional stability comparable to that of C60. The system allows us to study the effects of triangular frustration on the electronic properties of realistic solids, and it demonstrates a metal-insulator transition from that of graphene to a direct gap semiconductor in the visible blue region. By minimizing s-p orbital hybridization, which is an intrinsic property of carbon, not only the band edge states become nearly purely frustrated p states, but also the band structure is qualitatively different from any known bulk elemental semiconductors. For example, the optical properties are similar to those of direct-gap semiconductors GaN and ZnO, whereas the effective masses are comparable or smaller than those of Si.