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

## TL;DR

This paper provides a theoretical analysis of germagraphene, a graphene analogue, revealing how germanium doping affects its structure, electronic band-gap, and optical properties, with implications for optoelectronic applications.

## Contribution

It is the first theoretical study comparing two germagraphene structures and their electronic and optical properties, highlighting potential for optoelectronic devices.

## Key findings

- C16Ge is planar, C17Ge is buckled
- Both structures exhibit band-gaps due to Ge doping
- C17Ge has a 1.227 eV direct band-gap suitable for optoelectronics

## 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, C$_{17}$Ge and C$_{16}$Ge. In the C$_{17}$Ge structure, a germanium atom replaces a carbon atom while in C$_{16}$Ge structure, a carbon-carbon bond is replaced by a single germanium atom. These two types of doping have been experimentally made possible by Tripathi \etal [{\it{ACS Nano (2018) 1254641-4647}}]. We find that C$_{16}$Ge has a planar structure, whereas, the Ge atom in C$_{17}$Ge 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 C$_{17}$Ge is ideal for effective light absorbance and optoelectronic devices. Further study of optical properties supports this claim as well.