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Electronic properties of Co and Ni silicides: a theoretical approach using extended Huckel method
Author(s) -
Galvan D. H.,
Posada Amarillas A.,
Samaniego Reyna J. C.,
GarcíaMéndez M.,
Farías M. H.
Publication year - 2004
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200302056
Subject(s) - mulliken population analysis , atomic orbital , fermi level , charge density , density of states , extended hückel method , covalent bond , electronic structure , electronic band structure , population , charge (physics) , molecular orbital , orbital overlap , chemistry , hückel method , linear combination of atomic orbitals , materials science , density functional theory , atomic physics , condensed matter physics , computational chemistry , electron , physics , molecule , quantum mechanics , demography , organic chemistry , sociology
Calculations of electronic structure, total and projected density of states (DOS), crystal orbital overlap population (COOP), and average net charge, and also Mulliken population analysis, were performed to study electronic properties of Co and Ni silicides. Analysis of the energy bands depicts metallic behavior for both silicides. The projected DOS yields an indication that hybridization occurs for Co and Ni silicides. The hybridized band in CoSi 2 is composed of Co d and p orbitals and Si p and s orbitals, while in NiSi 2 the hybridized band is formed by Ni d and p orbitals with Si p orbitals. The fact that the Fermi energy crosses a small part of the DOS, as is the case of CoSi 2 , yields an indication of the different electronic properties of CoSi 2 when compared to NiSi 2 . The hybridization is stronger in CoSi 2 than in NiSi 2 . Mulliken population analysis provides an indication that a smaller charge distribution exists in NiSi 2 when compared to CoSi 2 . This difference in charge distribution accounts for the different electronic behavior, in agreement with the DOS analysis. Moreover, COOP analysis provides an indication of the existence of covalent bonding between M and Si (M = Ni, Co), this being stronger in Co than in Ni silicides. Furthermore, the average net charge in both compounds yields an indication that there is a charge transfer from M towards Si. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)