First-principles structure determination of interface materials: The NixInAs nickelides
Physical Review B - Condensed Matter and Materials Physics
American Physical Society
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We present here a first-principles study of the ternary compounds formed by Ni, In, and As, a material of great importance for self-aligned metallic contacts in next-generation InAs-based MOS transistors. The approach we outline is general and can be applied to study the crystal structure and properties of a host of other new interface compounds. Using the ab initio random structure searching approach we find the previously unknown low-energy structures of NixInAs and assess their stability with respect to the known binary compounds of Ni, In, and As. Guided by experiments, we focus on Ni3InAs and find a rich energy landscape for this stoichiometry. We consider the five lowest-energy structures, with space groups Pmmn, Pbcm, P21/m, Cmcm, and R3¯. The five low-energy structures for Ni3InAs are all found to be metallic and nonmagnetic. By comparison to previously published TEM results we identify the crystal structure observed in experiments to be Cmcm Ni3InAs. We calculate the work function for Cmcm Ni3InAs and, according to the Schottky-Mott model, expect the material to form an Ohmic contact with InAs. We further explicitly consider the interface between Cmcm Ni3InAs and InAs and find it to be Ohmic with an n-type Schottky barrier height of -0.55eV.
This work was supported in part by the EPSRC Grants No. EP/G007489/2, No. EP/J010863/1, and No. EP/I009973/1. All data supporting this study are provided as Supplemental Material accompanying this paper . Computational resources from the University College London and London Centre for Nanotechnology Computing Services as well as HECToR and Archer as part of the UKCP consortium are gratefully acknowledged.
This is the final version of the article. Available from American Physical Society via the DOI in this record.
Vol. 92, article 054105