Hybrid-Functional Calculations of the Copper Impurity in Silicon

Journal Article · Fri Aug 25 00:00:00 EDT 2017 · Physical Review Applied

DOI:https://doi.org/10.1103/physrevapplied.8.024023· OSTI ID:1535768

Sharan, Abhishek ^[1]; Gui, Zhigang ^[1]; Janotti, Anderson ^[1]

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1. Univ. of Delaware, Newark, DE (United States)

We calculate formation energies and transition levels for copper-related defects in silicon using the screened hybrid functional of Heyd, Scuseria, and Ernzerhof HSE06. We consider Cu siting on interstitial sites ( ${\mathrm{Cu}}_i$), a substitutional site ( ${\mathrm{Cu}}_{\mathrm{Si}}$), a ${\mathrm{Cu}}_{\mathrm{Si}}\text{-}{\mathrm{Cu}}_i$ pair, a complex formed from substitutional Cu and interstitial hydrogen ( ${\mathrm{Cu}}_{\mathrm{Si}}\text{-}{\mathrm{H}}_i$), and a complex formed from a substitutional Cu and three interstitial Cu atoms ( ${\mathrm{Cu}}_{\mathrm{Si}}\text{-}3{\mathrm{Cu}}_i$). We find that ${\mathrm{Cu}}_i$ is a fast diffuser, with a migration barrier of only 0.19 eV, in good agreement with experimental values. ${\mathrm{Cu}}_i$ is a shallow donor and its formation energy is lower than that of ${\mathrm{Cu}}_{\mathrm{Si}}$ for all Fermi-level positions in the band gap. ${\mathrm{Cu}}_{\mathrm{Si}}$, on the other hand, induces levels in the gap which are related to the occupation of antibonding states originating from the coupling between the Cu $3d$ states ( $t_2^{\left(d\right)}$), resonant in the valence band, and the vacancy-induced gap states ( $t_2^{\left(p\right)}$). The stable charge states of ${\mathrm{Cu}}_{\mathrm{Si}}$ in the gap are $+1$, 0, $-1$, and $-2$. The transition levels of ${\mathrm{Cu}}_{\mathrm{Si}}\text{-}{\mathrm{Cu}}_i$ and ${\mathrm{Cu}}_{\mathrm{Si}}\text{-}{\mathrm{H}}_i$ are closely related to the levels of isolated ${\mathrm{Cu}}_{\mathrm{Si}}$: a donor level ( $+/0$) near the valence band, an acceptor level near midgap, and a double-acceptor level in the upper part of the gap. Overall, the calculated transition levels are in good agreement with experimental results, and the formation energies explain the observed solubility.

• Research Organization: Univ. of California, Santa Barbara, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC); National Science Foundation (NSF)
• Grant/Contract Number: SC0014388; ACI-1053575
• OSTI ID: 1535768
• Alternate ID(s): OSTI ID: 1376923
• Journal Information: Physical Review Applied, Vol. 8, Issue 2; ISSN 2331-7019
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
electronic structure
point defects
elemental semiconductors
transition metals
band structure methods
density functional theory
hybrid functionals