Annealing mechanisms of intrinsic defects in 3C-SiC: a theoretical study

TL;DR

This theoretical study uses density functional theory to analyze the annealing mechanisms of intrinsic defects in 3C-SiC, revealing hierarchical processes driven by defect mobility and temperature, with implications for understanding defect evolution in irradiated SiC.

Contribution

It provides a detailed ab initio analysis of defect annealing pathways in 3C-SiC, highlighting the hierarchy of mechanisms and their temperature dependence.

Findings

Higher mobility of interstitials drives low-temperature annealing.

Interstitial clusters act as sources of carbon interstitials at high temperatures.

Silicon vacancy transforms into a more stable complex before migration in p-type material.

Abstract

The annealing kinetics of mobile intrinsic defects is investigated by an ab initio method based on density functional theory. The interstitial-vacancy recombination, the diffusion of vacancies and interstitials to defect sinks (e.g. surfaces or dislocations) as well as the formation of interstitial-clusters are considered. The calculated migration and reaction barriers suggest a hierarchical ordering of competing annealing mechanisms. The higher mobility of carbon and silicon interstitials as compared to the vacancies drives the annealing mechanims at lower temperatures including the vacancy-interstitial recombination and the formation of interstitial carbon clusters. These clusters act as a source for carbon interstials at elevated temperatures. In p-type material we discuss the transformation of the silicon vacancy into the more stable vacancy-antisite complex as an annealing mechanism, which is activated before the vacancy migration. Recent annealing studies of vacancy-related centers in irradiated 3C- and 4H-SiC and semi-insulating 4H-SiC are interpreted in terms of the proposed hierarchy of annealing mechanisms.