Diffusion of Ge below the Si(100) Surface: Theory and Experiment

Uberuaga, Blas P.; Leskovar, M.; Smith, Arthur P.; Jónsson, Hannes; Olmstead, Marjorie A.

doi:10.1103/physrevlett.84.2441

Cited by 82 publications

(84 citation statements)

References 26 publications

(28 reference statements)

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“…Although v 0 can be determined more exactly if required, 27 it is common practice to use a fixed preexponential factor of the order of 10 13 . 26,28 This value agrees with calculations done for single atom hops of Ag on a ZnO substrate showing that the pre-factors are typically between 0.3 Â 10 13 and 14 Â 10 13 . The reasoning for using a fixed value is that a more exact value can be very computational expensive to determine and the frequency of events from the Arrhenius equation depends more strongly on the value of E B than v 0 .…”

Section: A Akmcsupporting

confidence: 78%

Growth of silver on zinc oxide via lattice and off-lattice adaptive kinetic Monte Carlo

2018

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The growth of Ag on ZnO was modeled using a reactive force field potential and a combination of molecular dynamics and adaptive kinetic Monte Carlo (AKMC) simulations. An adaptive lattice-based AKMC model is described as a method of extending timescales and length scales that can be simulated. Reusing previously found transitions to reduce computational time is discussed for both the lattice and off-lattice AKMC approaches. With these methods, growth of over 1 monolayer's worth of Ag is simulated corresponding to a real deposition time of up to 0.1 s. The results show that the deposited silver aggregates on the surface through mainly single atom moves with few concerted motions. Initially silver adatoms do not agglomerate and the energy barriers for silver dimers to form are larger than for them to break apart. The first layer of silver grows as a series of connected regions rather than forming well-defined centro-symmetric islands.

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Section: A Akmcsupporting

confidence: 78%

Growth of silver on zinc oxide via lattice and off-lattice adaptive kinetic Monte Carlo

2018

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“…As such, the M ϫ N patch structure is described as an M ϫ 4 layer atop a 4 ϫ N layer, for which the upper layer does not fill in the preceding layer DVLs. Moreover, recent work 24,25 indicates that nontrivial intermixing is expected to occur across the Ge-Si interface.…”

Section: Introductionmentioning

confidence: 99%

Surface energetics and structure of the Ge wetting layer on Si(100)

2004

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Ge deposited on Si(100) initially forms heteroepitaxial layers, which grow to a critical thickness of ϳ3 MLs before the appearance of three-dimensional strain relieving structures. Experimental observations reveal that the surface structure of this Ge wetting layer is a dimer vacancy line (DVL) superstructure of the unstrained Ge(100) dimer reconstruction. In the following, the results of first-principles calculations of the thickness dependence of the wetting layer surface excess energy for the c͑4 ϫ 2͒ and 4 ϫ 6 DVL surface reconstructions are reported. These results predict a wetting layer critical thickness of ϳ3 MLs, which is largely unaffected by the presence of dimer vacancy lines. The 4 ϫ 6 DVL reconstruction is found to be thermodynamically stable with respect to the c͑4 ϫ 2͒ structure for wetting layers at least 2 ML thick. A strong correlation between the fraction of total surface induced deformation present in the substrate and the thickness dependence of wetting layer surface energy is also shown.

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“…The fourth contribution comes from the entropic term and favours alloying. As demonstrated by ab initio calculations [32,33], all mechanisms of atomic exchange responsible for intermixing are possible only within the first few atomic layers at the surface. In the bulk below, the activation barriers for atomic motions are too high and bulk diffusion is hindered.…”

Section: Intermixingmentioning

confidence: 99%

“…the MBE beam) and redistribution of atoms by diffusion along the surface. Bulk processes can be considered to play no role due to their higher activation barrier [32,58].…”

Section: Evolution Lawmentioning

confidence: 99%

“…Intermixing takes place also in InGaAs/GaAs [31], but the effect is less dramatic due to the non-negligible enthalpy of mixing. It is important to point out that, at the typical temperatures of interest, intermixing occurs only at the surface (or, at the subsurface) [32][33][34], as bulk diffusion is kinetically hindered. This observation is key, as, for any miscible system, deposition of a thin film on a thick substrate would lead to full dilution of the former in the latter, as determined by entropy maximization.…”

Section: Introductionmentioning

confidence: 99%

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Continuum modelling of semiconductor heteroepitaxy: an applied perspective

Bergamaschini

Salvalaglio

Backofen

et al. 2016

Advances in Physics: X

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Semiconductor heteroepitaxy involves a wealth of qualitatively different, competing phenomena. Examples include threedimensional island formation, injection of dislocations, mixing between film and substrate atoms. Their relative importance depends on the specific growth conditions, giving rise to a very complex scenario. The need for an optimal control over heteroepitaxial films and/or nanostructures is widespread: semiconductor epitaxy by molecular beam epitaxy or chemical vapour deposition is nowadays exploited also in industrial environments. Simulation models can be precious in limiting the parameter space to be sampled while aiming at films/nanostructures with the desired properties. In order to be appealing (and useful) to an applied audience, such models must yield predictions directly comparable with experimental data. This implies matching typical time scales and sizes, while offering a satisfactory description of the main physical driving forces. It is the aim of the present review to show that continuum models of semiconductor heteroepitaxy evolved significantly, providing a promising tool (even a working tool, in some cases) to comply with the above requirements. Several examples, spanning from the nanometre to the micron scale, are illustrated. Current limitations and future research directions are also discussed.

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Diffusion of Ge below the Si(100) Surface: Theory and Experiment

Cited by 82 publications

References 26 publications

Growth of silver on zinc oxide via lattice and off-lattice adaptive kinetic Monte Carlo

Growth of silver on zinc oxide via lattice and off-lattice adaptive kinetic Monte Carlo

Surface energetics and structure of the Ge wetting layer on Si(100)

Continuum modelling of semiconductor heteroepitaxy: an applied perspective

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