Trap mutation in He-doped ion-implanted tungsten

Keriem, M.S. Abd El; Werf, D. P. van der; Pleiter, F.

doi:10.1007/bf00567609

Cited by 24 publications

(11 citation statements)

References 8 publications

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“…During annealing, single Ar atoms were observed to migrate from areas of a low concentration of Ar to areas of higher concentration. Usually the resulting clusters consisted of interstitial atoms but in a few cases there was evidence of a trap mutation mechanism [33] where a lattice atom is ejected as an interstitial and is replaced by a gas atom; this only occurs when a cluster reaches a size containing at least 6 Ar atoms. The consequence of this is that large clusters can become 'pinned' to their location since substitutional Ar atoms are more strongly bound.…”

Section: (Ii) Annealing Simulationsmentioning

confidence: 99%

Inert gas bubble formation in magnetron sputtered thin-film CdTe solar cells

et al. 2020

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Cadmium telluride (CdTe) solar cells are deposited in current production using evaporation-based tech- niques. Fabricating CdTe solar cells using magnetron sputtering would have the advantage of being more cost-efficient. Here, we show that such deposition results in the incorporation of the magnetron working gas Ar, within the films. Post deposition processing with CdCl 2 improves cell efficiency and during which stacking faults are removed. The Ar then accumulates into clusters leading to the creation of voids and blisters on the surface. Using molecular dynamics, the penetration threshold energies are determined for both Ar and Xe, with CdTe in both zinc-blende and wurtzite phases. These calculations show that more Ar than Xe can penetrate into the growing film with most penetration across the (111) surface. The mechanisms and energy barriers for interstitial Ar and Xe diffusion in zinc-blende are determined. Barriers are reduced near existing clusters, increasing the probability of capture-based cluster growth. Barriers in wurtzite are higher with non-Arrhenius behaviour observed. This provides an explanation for the increase in the size of voids observed after stacking fault removal. Blister exfoliation was also modelled, showing the formation of shallow craters with a raised rim.

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Section: (Ii) Annealing Simulationsmentioning

confidence: 99%

Inert gas bubble formation in magnetron sputtered thin-film CdTe solar cells

et al. 2020

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“…It is generally agreed that the formation of a bubble can present areas of high strain fields and can easily initiate a failure by embrittlement or stress cracking. The common character of the several mechanisms proposed for the formation of H and He bubbles is that vacancy-hydrogen and vacancy-helium clusters can grow to form H and He bubbles, respectively [31][32][33]. However, a vacancy-hydrogen (-helium) cluster decomposes with increasing temperature [17,33].…”

Section: Introductionmentioning

confidence: 99%

Clustering of H and He, and their effects on vacancy evolution in tungsten in a fusion environment

You¹,

Li²,

Kong³

et al. 2014

Nucl. Fusion

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The behaviours of hydrogen and helium in tungsten are vitally important in fusion research because they can result in the degradation of the material. In the present work, we carry out density-functional theory calculations to investigate the clustering of hydrogen and helium atoms at interstitial sites, vacancy and small vacancy clusters (Vac m , m = 2, 3), and the influence of hydrogen and helium on vacancy evolution in tungsten. We find that hydrogen atoms are extremely difficult to aggregate at interstitial sites to form a stable cluster in tungsten. However, helium atoms are energetically favourable to cluster together in a close-packed arrangement between (1 1 0) planes forming helium monolayer structure, where the helium atoms are not perfectly in one plane. Both hydrogen and helium prefer to aggregate stably in vacancy and small vacancy cluster forming Vac m X n (X = H, He). The concentrations of Vac m H n (m = 1) clusters relative to temperature are evaluated through the law of mass action. The present calculations also show that the emission of a 1 1 1 dumbbell self-interstitial atom (SIA) from He n to form VacHe n and from VacHe n to form Vac 2 He n may take place for n > 5 and n > 9, respectively. According to the present results, we predict that a helium monolayer structure could nucleate for He atom platelet lying on (1 1 0) plane in tungsten, and the helium platelet formation on (1 1 0) plane in molybdenum observed by the experiment may be due to the initial monolayer arrangement of He atoms at interstitial sites. Meanwhile, our results contribute to the understanding for nucleation and the development of the voids and blisters in tungsten that are observed in the experiments.

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“…Those events have been evidenced in MD simulations by many authors [34][35][36] and are favored by the potentials used for these MD simulations.…”

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confidence: 75%