Coupled electronic and atomic effects on defect evolution in silicon carbide under ion irradiation

Understanding energy dissipation processes in electronic/atomic subsystems and subsequent non equilibrium defect evolution is a long-standing challenge in materials science. In the intermediate energy regime, energetic particles simultaneously deposit a significant amount of energy to both electronic and atomic subsystems of silicon carbide (SiC). Here we show that defect evolution in SiC closely depends on the electronic-to-nuclear energy loss ratio (S-e/S-n), nuclear stopping powers (dE/dx(nucl)), electronic stopping powers (dE/dx(ele)), and the temporal and spatial coupling of electronic and atomic subsystem for energy dissipation. The integrated experiments and simulations reveal that: (1) increasing S-e/S-n, slows damage accumulation; (2) the transient temperatures during the ionization-induced thermal spike increase with dE/dx(ele), which causes efficient damage annealing along the ion trajectory; and (3) for more condensed displacement damage within the thermal spike, damage production is suppressed due to the coupled electronic and atomic dynamics. Ionization effects are expected to be more significant in materials with covalent/ionic bonding involving predominantly well-localized electrons. Insights into the complex electronic and atomic correlations may pave the way to better control and predict SiC response to extreme energy deposition. (C) 2017 Elsevier Ltd. All rights reserved.