Electronic and optical properties of Germagraphene, a direct band-gap semiconductor

Abstract

In this communication, we report a theoretical attempt to understand the electronic and optical properties of germagraphene, a two-dimensional graphene analogue. We study two different structures, C17Ge and C16Ge. In the C17Ge structure, a germanium atom replaces a carbon atom while in C16Ge structure, a carbon-carbon bond is replaced by a single germanium atom. These two types of doping have been experimentally made possible by Tripathi et al. [ACS Nano (2018) 1254641-4647]. We find that C16Ge has a planar structure, whereas, the Ge atom in C17Ge settles in an out-of-the plane position, resulting in a buckled structure. Due to Ge doping, the band-gaps open up in both. The 1.227 eV direct gap of C17Ge is ideal for effective light absorbance and optoelectronic devices. Further study of optical properties supports this claim as well.