Abstract
In this study, an ab initio molecular dynamics method is employed to investigate how the existence of stacking faults (SFs) influences the response of SiC to low energy irradiation. It reveals that the C and Si atoms around the SFs are generally more difficult to be displaced than those in unfaulted SiC, and the corresponding threshold displacement energies for them are generally larger, indicative of enhanced radiation tolerance caused by the introduction of SFs, which agrees well with the recent experiment. As compared with the unfaulted state, more localized point defects are generated in faulted SiC. Also, the efficiency of damage production for Si recoils is generally higher than that of C recoils. The calculated potential energy increases for defect generation in SiC with intrinsic and extrinsic SFs are found to be higher than those in unfaulted SiC, due to the stronger screen-Coulomb interaction between the PKA and its neighbors. The presented results provide a fundamental insight into the underlying mechanism of displacement events in faulted SiC and will help to advance the understanding of the radiation response of SiC with and without SFs.
Highlights
In this study, an ab initio molecular dynamics method is employed to investigate how the existence of stacking faults (SFs) influences the response of SiC to low energy irradiation
It has been revealed that physical parameters like threshold displacement energy can be determined with ab initio accuracy, and new mechanism for defect generation and new defective states that are different from classical molecular dynamics (MD) can be predicted
Edef is the energy of the faulted supercell, tsecEplahirnoultieientteceedrcdoenrghfniitaeefii-:osamsrμlritaschimsrcihoeea≤fa(elctbμnapiuμosleoiclsrnktui=ge(lSybneaiμutntoieialsefadkinr(lt)dhbgu,oμueinfdelcduisksapen≤)mreufacabnonμiuoneddclstdt(ehμeb,rid.crucTebals=kshurop)bpeteμaoheccnsnrihtccdci-e(veroμbmelinlclus,yihid∆lc,k+i(aat)nμlniiμo−cpdincos=μsμtt=eshisμcnaie((μrctbbcie(sahiuubclfallu(skkonblo))kuug)f)inelscksadioit)nnlh,nidtcwetdoohμthinotesebiitorn(ae=eμnul μ.nSemiμFns)eibose(aaiecbrrrng(rlutdbyyohlukcfeoi)ladsfktarph)benbenru−doceltinekμiecμstcS(ayμ(ciilpCb((cbiu)et2uos8=lo.klobkT)efSe)haa)iIyrecSceohtFSorhtFshnCeo,edft)tfoihhcoatrheilenmolerocdnm,aawμtliaiici.cnioneuaind.gs-l, ~−7.8 mJ/m2, which agrees well with the value of −3.4 mJ/m2 reported by Käckell et al.[29]
Summary
An ab initio molecular dynamics method is employed to investigate how the existence of stacking faults (SFs) influences the response of SiC to low energy irradiation. It reveals that the C and Si atoms around the SFs are generally more difficult to be displaced than those in unfaulted SiC, and the corresponding threshold displacement energies for them are generally larger, indicative of enhanced radiation tolerance caused by the introduction of SFs, which agrees well with the recent experiment. Jamison et al have investigated how the SFs influence the dose to amorphization in SiC and found that the energy barriers for Si interstitial migration and the rate-limiting defect recovery reaction are reduced by the existence of SFs18 In spite of these extensive studies, the dynamic processes for defect generation in SF-contained SiC at an atomic level have not been revealed yet. Our main aims are (1) to investigate the defect generation mechanism and defect distribution in SiC with SFs; (2) to compare the response of unfaulted and faulted SiC to low energy radiation; and (3) to explore the origin of the difference in the radiation susceptibility between SF-contained SiC and the unfaulted state
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