Amorphous defect clusters of pure Si and type inversion in Si detectors

Holmström, Eero; Nordlund, K.; Hakala, Mikko

doi:10.1103/physrevb.82.104111

Cited by 16 publications

(15 citation statements)

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“…A recent study points out that amorphous pockets are strong acceptors of electrons and may be responsible for the deleterious type inversion observed in Si detectors. 18 Caturla et al showed that the local melting process in Si presented a strong dependence on ion mass: it is almost negligible for light ions, but it may lead to the formation of large amorphous regions when heavy ions are implanted. 17 Thermal spikes may be especially relevant in Ge, due to its lower melting temperature.…”

Section: Introductionmentioning

confidence: 99%

Molecular dynamics simulations of damage production by thermal spikes in Ge

López¹,

Pelaz²,

Santos³

et al. 2012

Journal of Applied Physics

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Molecular dynamics simulation techniques are used to analyze damage production in Ge by the thermal spike process and to compare the results to those obtained for Si. As simulation results are sensitive to the choice of the inter-atomic potential, several potentials are compared in terms of material properties relevant for damage generation, and the most suitable potentials for this kind of analysis are identified. A simplified simulation scheme is used to characterize, in a controlled way, the damage generation through the local melting of regions in which energy is deposited. Our results show the outstanding role of thermal spikes in Ge, since the lower melting temperature and thermal conductivity of Ge make this process much more efficient in terms of damage generation than in Si. The study is extended to the modeling of full implant cascades, in which both collision events and thermal spikes coexist. Our simulations reveal the existence of bigger damaged or amorphous regions in Ge than in Si, which may be formed by the melting and successive quenching induced by thermal spikes. In the particular case of heavy ion implantation, defect structures in Ge are not only bigger, but they also present a larger net content in vacancies than in Si, which may act as precursors for the growth of voids and the subsequent formation of honeycomb-like structures.

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Section: Introductionmentioning

confidence: 99%

Molecular dynamics simulations of damage production by thermal spikes in Ge

López¹,

Pelaz²,

Santos³

et al. 2012

Journal of Applied Physics

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“…In this work only 17 atoms are taken to form an amorphous region -one has chosen a central atom, its four nearest neighbours and twelve next-nearest neighbours. A smaller than in [11] number of atoms in the cluster was necessary to be able to run time consuming DFT molecular dynamics structure relaxations. We have calculated DOS for 25 randomly created different clusters and have run cluster relaxation for 10 of them.…”

Section: Electron States In the Disordered Defect Clustermentioning

confidence: 99%

“…The first (and the single so far) attempt to simulate larger defect clusters in silicon containing up to 50 randomly displaced atoms within the amorphous region of ~1 nm in diameter by the DFT method was reported in [11]. The main result of these calculations was the presence of the localized states within the cluster of both the donor and acceptor types with the corresponding energy levels in the forbidden energy gap.…”

Section: Introductionmentioning

confidence: 99%

“…In this work we have performed similar DFT studies of disordered clusters in a silicon crystal. Contrary to the approach done in [11], where the relaxation of the disordered cluster was simulated by a molecular dynamics annealing procedure with empirically defined inter atomic forces, the simulation of the relaxation in this work is done by applying molecular dynamics where atomic forces have been calculated by the DFT method. Relaxation of the atoms driven by empirical forces could lead to the states with incorrectly restored inter atomic covalent bonds and to the existence of artifact states.…”

Section: Introductionmentioning

confidence: 99%

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Disordered small defect clusters in silicon

Ža̧sinas¹

2016

Lith. J. Phys.

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The ionizing radiation induced disordered defect clusters and their relaxation in silicon were simulated by the density functional method. It was found that a non-relaxed disordered cluster gives rise to a great number of localized states having their energy levels within the semiconductor forbidden band gap. After the relaxation, however, the density of these states significantly decreases leaving only several relatively shallow donor and acceptor state levels that may contribute to trapping of free carriers and shrinkage of an effective band gap.

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“…Under certain circumstances, the nonlinear component of the irradiating ion's energy is effectively operative and can generate localized thermal spikes whose experimental evidence, theoretical interpretations and MD simulations have established the conditions for various ion-target combinations and the ion-energy dependence. Comprehensive summaries of the individual, combined and the relative effects of the cascades and spikes has been provided in various reports and reviews [19][20][21][22]. The irradiation effects in carbon nanostructures have been investigated in recent years due to the potential applications of graphene and nanotubes [23,24].…”

Section: Introductionmentioning

confidence: 99%

An information theoretic model for the linear and nonlinear dissipative structures in irradiated single-walled carbon nanotubes

Ashraf

Javeed

Zeeshan

et al. 2018

Chemical Physics Letters

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Experiments with irradiated single-walled carbon nanotubes are shown to generate a set of probability distribution functions and to derive a set of information theoretic entropy-based parameters. Energetic Cs + ions initiate linear collision cascades and nonlinear thermal spikes in single-walled carbon nanotubes. The probability distribution functions are constructed from the normalized experimental yields of the sputtered atoms and clusters. The information or Shannon entropy and fractal dimension are evaluated for each of the emitted species. Along with the fractal dimension, the information is used to identify and distinguish the energy dissipation processes that generate conditions for monatomic sputtering and clusters emissions.

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Amorphous defect clusters of pure Si and type inversion in Si detectors

Cited by 16 publications

References 50 publications

Molecular dynamics simulations of damage production by thermal spikes in Ge

Molecular dynamics simulations of damage production by thermal spikes in Ge

Disordered small defect clusters in silicon

An information theoretic model for the linear and nonlinear dissipative structures in irradiated single-walled carbon nanotubes

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