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Formation of Nanotwin Networks during High-Temperature Crystallization of Amorphous Germanium.

Sandoval L, Reina C, Marian J - Sci Rep (2015)

Bottom Line: We find that crystallization occurs by the recurrent transfer of atoms via a diffusive process from the amorphous phase into suitably-oriented crystalline layers.We accompany our simulations with a comprehensive thermodynamic and kinetic analysis of the growth process, which explains the energy balance and the interfacial growth velocities governing grain growth.We calculate the equivalent X-ray diffraction pattern of the obtained nanotwin networks, providing grounds for experimental validation.

View Article: PubMed Central - PubMed

Affiliation: Los Alamos National Laboratory, Los Alamos, NM 87545, United States.

ABSTRACT
Germanium is an extremely important material used for numerous functional applications in many fields of nanotechnology. In this paper, we study the crystallization of amorphous Ge using atomistic simulations of critical nano-metric nuclei at high temperatures. We find that crystallization occurs by the recurrent transfer of atoms via a diffusive process from the amorphous phase into suitably-oriented crystalline layers. We accompany our simulations with a comprehensive thermodynamic and kinetic analysis of the growth process, which explains the energy balance and the interfacial growth velocities governing grain growth. For the 〈111〉 crystallographic orientation, we find a degenerate atomic rearrangement process, with two zero-energy modes corresponding to a perfect crystalline structure and the formation of a Σ3 twin boundary. Continued growth in this direction results in the development a twin network, in contrast with all other growth orientations, where the crystal grows defect-free. This particular mechanism of crystallization from amorphous phases is also observed during solid-phase epitaxial growth of 〈111〉 semiconductor crystals, where growth is restrained to one dimension. We calculate the equivalent X-ray diffraction pattern of the obtained nanotwin networks, providing grounds for experimental validation.

No MeSH data available.


Related in: MedlinePlus

Schematic view along the  direction of the Ge diamond cubic lattice, with the  plane highlighted.Image obtained with Wolfram CDF Player48.
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f8: Schematic view along the direction of the Ge diamond cubic lattice, with the plane highlighted.Image obtained with Wolfram CDF Player48.

Mentions: To ascertain which mechanism is responsible for the observed formation of nanotwin networks, next we carry out MD simulations of a/c bi-crystals at T0 oriented along three selected directions: [111] (low mobility, cf. Figs 2 and 4), and [100] and [110] (high mobility). These are qualitatively similar to other simulations of the SPER process using atomistic methods343536. The three surface orientations simulated here are schematically shown in Fig. 8 relative to a view of the Ge diamond cubic lattice.


Formation of Nanotwin Networks during High-Temperature Crystallization of Amorphous Germanium.

Sandoval L, Reina C, Marian J - Sci Rep (2015)

Schematic view along the  direction of the Ge diamond cubic lattice, with the  plane highlighted.Image obtained with Wolfram CDF Player48.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4660462&req=5

f8: Schematic view along the direction of the Ge diamond cubic lattice, with the plane highlighted.Image obtained with Wolfram CDF Player48.
Mentions: To ascertain which mechanism is responsible for the observed formation of nanotwin networks, next we carry out MD simulations of a/c bi-crystals at T0 oriented along three selected directions: [111] (low mobility, cf. Figs 2 and 4), and [100] and [110] (high mobility). These are qualitatively similar to other simulations of the SPER process using atomistic methods343536. The three surface orientations simulated here are schematically shown in Fig. 8 relative to a view of the Ge diamond cubic lattice.

Bottom Line: We find that crystallization occurs by the recurrent transfer of atoms via a diffusive process from the amorphous phase into suitably-oriented crystalline layers.We accompany our simulations with a comprehensive thermodynamic and kinetic analysis of the growth process, which explains the energy balance and the interfacial growth velocities governing grain growth.We calculate the equivalent X-ray diffraction pattern of the obtained nanotwin networks, providing grounds for experimental validation.

View Article: PubMed Central - PubMed

Affiliation: Los Alamos National Laboratory, Los Alamos, NM 87545, United States.

ABSTRACT
Germanium is an extremely important material used for numerous functional applications in many fields of nanotechnology. In this paper, we study the crystallization of amorphous Ge using atomistic simulations of critical nano-metric nuclei at high temperatures. We find that crystallization occurs by the recurrent transfer of atoms via a diffusive process from the amorphous phase into suitably-oriented crystalline layers. We accompany our simulations with a comprehensive thermodynamic and kinetic analysis of the growth process, which explains the energy balance and the interfacial growth velocities governing grain growth. For the 〈111〉 crystallographic orientation, we find a degenerate atomic rearrangement process, with two zero-energy modes corresponding to a perfect crystalline structure and the formation of a Σ3 twin boundary. Continued growth in this direction results in the development a twin network, in contrast with all other growth orientations, where the crystal grows defect-free. This particular mechanism of crystallization from amorphous phases is also observed during solid-phase epitaxial growth of 〈111〉 semiconductor crystals, where growth is restrained to one dimension. We calculate the equivalent X-ray diffraction pattern of the obtained nanotwin networks, providing grounds for experimental validation.

No MeSH data available.


Related in: MedlinePlus