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Topological insulators from the perspective of first-principles calculations

  1. Top of page
  2. Topological insulators from the perspective of first-principles calculations
  3. Quantification of local geometry and local symmetry in models of disordered materials
  4. Defect generation, advanced crystalliza-tion, and characterization methods for high-quality solar-cell silicon

Haijun Zhang and Shou-Cheng Zhang

First-principles calculations play a crucial role in the field of topological insulators. This review briefly reports the widely-used techniques of first-principles calculations and the current progress in this field. Though many topological insulators have been dis-covered, it is still important to find more with desired properties, for example, a bigger band gap, multifunctional properties with topology. This review is expected to guide following works in this field.

Part of Focus Issue on Topological Insulators - From Materials Design to Reality (Eds.: Claudia Felser, Shoucheng Zhang, Binghai Yan)

Phys. Status Solidi RRL (2012) DOI 10.1002/pssr.201206414

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Quantification of local geometry and local symmetry in models of disordered materials

  1. Top of page
  2. Topological insulators from the perspective of first-principles calculations
  3. Quantification of local geometry and local symmetry in models of disordered materials
  4. Defect generation, advanced crystalliza-tion, and characterization methods for high-quality solar-cell silicon

Matthew J. Cliffe and Andrew L. Goodwin

Cliffe and Goodwin suggest two metrics for assessing the quality of configurations of disordered materials: namely, local geometric invariance and degree of local symmetry. These enable screening for structural simplicity in a way that does not rely on formal group theoretical language (and hence long-range periodic order). The authors show that various SiO2 and a-Si configurations are ranked sensibly by this approach, which is found to be significantly more sensitive to unphysical features than pairwise correlations.

Phys. Status Solidi B (2012) DOI 10.1002/pssb.201248553

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Defect generation, advanced crystalliza-tion, and characterization methods for high-quality solar-cell silicon

  1. Top of page
  2. Topological insulators from the perspective of first-principles calculations
  3. Quantification of local geometry and local symmetry in models of disordered materials
  4. Defect generation, advanced crystalliza-tion, and characterization methods for high-quality solar-cell silicon

Marisa Di Sabatino and Gaute Stokkan

In this Feature Article, research work on solar cell silicon materials is reviewed, particularly the recent state-of-the-art research activities at the Norwegian University of Science and Technology (NTNU) on defects, crystallization and characterization. Control of nucleation and growth during the crystallization of the silicon ingots allows for control of the materials structure development. The authors show that a high initial cooling rate can give ingots with larger grains and preferred crystal orientation. Such control of nucleation conditions, although difficult to achieve in practice, appears to be a very important prerequisite for producing low defect density materials and, hence, high performance solar cells. Combination of advanced characterization tools allows for an in-depth study of materials properties and is important for tailoring the investigation from macro- to microscale.

Phys. Status Solidi A (2012) DOI 10.1002/pssa.201200639

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