Evolution of small defect clusters in ion-irradiated 3C-SiC: combined cluster dynamics modeling and experimental study

TL;DR

This study combines experimental microscopy and cluster dynamics modeling to investigate defect evolution in ion-irradiated 3C-SiC, revealing limitations of existing models and identifying additional phenomena influencing defect clustering.

Contribution

The paper introduces an enhanced cluster dynamics model for SiC that incorporates additional phenomena beyond point defect reactions, improving agreement with experimental observations.

Findings

Most small clusters are invisible in TEM but detectable in STEM.

Standard models based on point defects alone fail to predict defect distributions accurately.

Additional phenomena are necessary to match experimental cluster distributions.

Abstract

Distribution of black spot defects and small clusters in 1 MeV krypton irradiated 3C-SiC has been investigated using advanced scanning transmission electron microscopy (STEM) and TEM. We find that two thirds of clusters smaller than 1 nm identified in STEM are invisible in TEM images. For clusters that are larger than 1 nm, STEM and TEM results match very well. A cluster dynamics model has been developed for SiC to reveal processes that contribute to evolution of defect clusters and validated against the (S)TEM results. Simulations showed that a model based on established properties of point defects (PDs) generation, reaction, clustering, and cluster dissociation, is unable to predict black spot defects distribution consistent with STEM observations. This failure suggests that additional phenomena not included in a simple point-defect picture may contribute to radiation-induced evolution of defect clusters in SiC and using our model we have determined the effects of a number of these additional phenomena on cluster evolution. Using these additional phenomena it is possible to fit parameters within physically justifiable ranges that yield agreement between cluster distributions predicted by simulations and those measured experimentally.