Thermoelectric Properties of Silicon Carbide Nanowires with Nitrogen Dopants and Vacancies

TL;DR

This study theoretically investigates how nitrogen doping and vacancies in silicon carbide nanowires can significantly improve their thermoelectric efficiency, achieving a ZT value of 1.78 at high temperature.

Contribution

It reveals optimal dopant and vacancy configurations in SiC nanowires to maximize thermoelectric performance, providing insights for material design.

Findings

ZT can reach 1.78 at 900K for specific configurations.

N doping combined with Si vacancies enhances thermoelectric properties.

Optimal vacancy locations depend on doping type and nanowire geometry.

Abstract

The thermoelectric properties of cubic zincblend silicon carbide nanowires (SiCNWs) with nitrogen impurities and vacancies along [111] direction are theoretically studied by means of atomistic simulations. It is found that the thermoelectric figure of merit ZT of SiCNWs can be significantly enhanced by doping N impurities together with making Si vacancies. Aiming at obtaining a large ZT, we study possible energetically stable configurations, and disclose that, when N dopants locate at the center, a small number of Si vacancies at corners are most favored for n-type nanowires, while a large number of Si vacancies spreading into the flat edge sites are most favored for p-type nanowires. For the SiCNW with a diameter of 1.1 nm and a length of 4.6 nm, the ZT value for the n-type is shown capable of reaching 1.78 at 900K. The conditions to get higher ZT values for longer SiCNWs are also addressed.