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Band parameters of Ga2O3, In2O3, and their alloys

 

 

Overview of the research project:

The band gap of (GaxIn1-x)2O3 can be tuned by adjusting the Ga/In ratio (e.g. from 3.8 eV to ca. 5 eV)1. However, with the exception of very recent theoretical work for GaInO3,2 a detailed computational investigation for the properties of the ternary materials is still lacking.

Technological application and device simulations depend on band parameters, including the effective masses of electrons and holes. Recent theoretical work of the FHI group on “strain effects and band parameters” in MgO, ZnO, CdO, and group-III nitrides has demonstrated the methodology of such studies and the significant insight they provide.3,4 The present project will extend this methodology to GaIn-oxides. The significantly larger unit cells of these materials, the particularly difficult treatment of oxygen (with respect to exchange and correlation), as well as the tendency towards polaron formation, impose significant challenges and require advancements of the existing theoretical methods.

The project builds on the structure and stability search and analysis that is performed by Chris Sutton.

It is planned to combine the density-funtional theory (DFT) and GW calculations with machine-learning to handle the high number of possible alloys as well as the large unit cells of some materials. The latter will be used in an “active-learning” strategy, i.e., making “educated suggestions” for what material (crystal structure and Ga/In ratio) should be studied next by expensive DFT calculations. This helps to add new materials that have noticeably different properties and reduces the risk´calculating redundant information. These new DFT results will then be used for the next iteration (or an update of) of machine learning.

 

(1) Zhang, F.; Saito, K.; Tanaka, T.; Nishio, M.; Guo, Q. Solid State Communications 2014, 186, 28.
(2) Wang, V.; Xiao, W.; Ma, D.-M.; Liu, R.-J.; Yang, C.-M. Journal of Applied Physics 2014, 115, 043708.
(3) Rinke, P., M. Winkelnkemper, A. Qteish, D. Bimberg, J. Neugebauer, and M. Scheffer: Consistent set of band parameters for the group-III nitrides AlN, GaN, and InN. Phys. Rev. B 77, 075202 (2008).
(4) Yan, Q., P. Rinke, M. Winkelnkemper, A. Qteish, D. Bimberg, M. Scheffer, and C.G. Van de Walle: Strain effects and band parameters in MgO, ZnO, and CdO. Appl. Phys. Lett. 101, 152105 (2012).


Major accomplishments expected:

  • Method development for calculating reliable data for band parameters of GaIn oxides (DFT, advanced xc functionals, GW).
  • New methodology for machine learning of band parameters.
  • Quantitative results for different alloys and different crystal structures.
  • A systematic and very extensive data base based on machine learning.

 

Collaboration with partners in the project:

  • PDI

 

Collaboration with partners in other projects:

  • Materials growth: IKZ & PDI / Projects 8, 9, 11 & 12 (C3)
  • Structure analysis: IKZ & PDI / Projects 10 (C3) & 15 (C4)
  • Point defects: IKZ / Project 16 (C4)
  • Theory: HU & FHI / Project 13 (C4)

The Research Team

 

Christian Vorwerk

Christopher Sutton
PostDoc

Christopher Sutton is from Arkansas, USA. He received his PhD at the Georgia Institute of Technology with a 6-month postdoc at Duke University, mostly modeling photophysical properties of organic materials. He joined GraFOx through the Fritz-Haber-Institut because of an interest in method-development to facilitate the design of new materials. The diverse background of researchers within the Science Campus is great opportunity for computational predictions to be tested by collaborators that in turn facilitates the refinement of the theoretical methods.

 


Project lead

If you have queries about the project, please contact the PI:
Matthias Scheffler, Fritz-Haber-Institut

 

Logo_Fritz Haber Institut

coordination:
Paul-Drude-Institut für
Festkörperelektronik
Leibniz-Insitut im Forschungsverbund Berlin e.V.
Hausvogteiplatz 5-7
10117 Berlin, Germany 

The Leibniz ScienceCampus GraFOx is a network of two Leibniz institutes, two universities and one institute of the Max Planck Society. The Network is based in Berlin, Germany.

 

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