Damage buildup in Ar-ion-irradiated 3C-SiC at elevated temperatures

Abstract

Above room temperature, the accumulation of radiation damage in 3C-SiC is strongly influenced by dynamic defect interaction processes and remains poorly understood. Here, we use a combination of ion channeling and transmission electron microscopy to study lattice disorder in 3C-SiC irradiated with 500 keV Ar ions in the temperature range of 25–250 °C. Results reveal sigmoidal damage buildup for all the temperatures studied. For 150 °C and below, the damage level monotonically increases with ion dose up to amorphization. Starting at 200 °C, the shape of damage–depth profiles becomes anomalous, with the damage peak narrowing and moving to larger depths and an additional shoulder forming close to the ion end of range. As a result, damage buildup curves for 200 and 250 °C exhibit an anomalous two-step shape, with a damage saturation stage followed by rapid amorphization above a critical ion dose, suggesting a nucleation-limited amorphization behavior. Despite their complexity, all damage buildup curves are well described by a phenomenological model based on an assumption of a linear dependence of the effective amorphization cross section on ion dose. In contrast to the results of previous studies, 3C-SiC can be amorphized by bombardment with 500 keV Ar ions even at 250 °C with a relatively large dose rate of ∼2×1013 cm−2 s−1, revealing a dominant role of defect interaction dynamics at elevated temperatures.

The amorphization of 3C-SiC irradiated at moderately elevated temperatures as revealed by X-ray diffraction

“…Furthermore, in Ref. [19], a comprehensive analysis of RBS/Cderived depth profiles of disorder revealed anomalous features and pointed out to the crucial importance of radiation defect dynamics, as also confirmed in two other studies [20,21].…”

“…From an experimental standpoint, apart from reports focused on the specific case of He-ion-induced damage in SiC [17,18], one can cite systematic studies reported by Weber et al [8] as well as by some of the present authors [19]. In both of these studies [8,19], the level of damage was quantitatively determined by Rutherford backscattering spectrometry in channeling mode (RBS/C). Both works provided evidence that, even at moderate temperatures of 250 °C and below, 3C-SiC undergoes pronounced dynamic annealing involving enhanced defect recombination.…”

Effects of collision cascade density on radiation defect dynamics in 3C-SiC

“…1(b). These observations are in agreement with results of our recent systematic study15 of the T -dependence of damage buildup in 3 C -SiC under 500 keV Ar ion bombardment.…”

“…15) is the maximum saturation fraction of defect clusters in the lattice, h(x ) is the Heaviside step function [ h(x ) = 0 for x  < 0 and h(x ) = 1 for x  ≥ 0], Φ crit is the critical dose above which amorphization proceeds, and ξ amorph is the amorphization cross-section constant.…”

“…The profile for Ar ions is taken from ref. 15. ( c ) Selected depth profiles of relative disorder in 3 C -SiC bombarded with pulsed Ne (open symbols) or Xe (closed symbols) ion beams to Φs of 0.4 and 0.32 DPA, respectively, with different values of t off (indicated in the legend in ms), t on  = 1 ms, and F on  = 1.9 × 10 13  cm −2 s −1 .…”