DFT modelling of the edge dislocation in 4H-SiC

J Łażewski,P T Jochym,K Parlinski,M Sternik,P Dłużewski,P Piekarz,J Cholewiński,S Krukowski

doi:10.1007/s10853-019-03630-5

Abstract

We have presented ab initio study, based on density functional theory methods, of full-core edge dislocation impact on basic properties of 4H-SiC semiconductor. To enable calculations in periodic boundary conditions, we have proposed geometry with two dislocations with opposite Burgers vectors. For this geometry, which determines the distance between dislocations, we have estimated the creation energy per unit length of a single-edge dislocation. The radial distribution function has been used to assess the effect of the dislocations on the local crystal structure. The analysis of the electronic structure reveals mid-gap p states induced by broken atomic bonds in the dislocation core. The maps of charge distribution and electrostatic potential have been calculated, and the significant decrease in the electrostatic barriers in the vicinity of the dislocation cores has been quantified. The obtained results have been discussed in the light of previous findings and calculations based mainly on phenomenological models.

Highlights

The silicon carbide (SiC), a wide band gap semiconductor, is a promising material for high-voltage and high-frequency nanoelectronic devices [1, 2]
We have successfully modelled a pair of edge dislocations using ab initio methods
We have shown that (i) the crystal structure is strongly disturbed in the small vicinity of the dislocation core, (ii) additional energy levels occurring in the energy gap belong to the atoms with broken bonds occupying the core neighbourhood, (iii) existence of spatial tunnels, with atoms delivering localised states to the band structure on its sides, significantly decreases electrostatic barriers and should be considered as one of the primary factors responsible for experimentally observed reduction in breakdown voltage

Summary

Introduction

The silicon carbide (SiC), a wide band gap semiconductor, is a promising material for high-voltage and high-frequency nanoelectronic devices [1, 2]. Very good operational quality of SiC results from high values of breakdown voltage (% 106 V/cm), high charge carrier mobility, high temperature stability and high thermal conductivity [3]. This material has very good mechanical properties and resistance to radiation damage. The presence of intrinsic defects and impurities which arise during crystal growth process substantially limit applications of SiC. Dislocations are the main crystal defects in SiC

Methods

Results

Conclusion