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Electrical resistivity of Tin+1ACn (A = Si, Ge, Sn, n = 1–3) thin films

Published online by Cambridge University Press:  31 January 2011

Jens Emmerlich*
Affiliation:
Thin Film Physics Division, Department of Physics, Chemistry, and Biology, IFM, Linköping University, SE-581 83 Linköping, Sweden
Per Eklund
Affiliation:
Thin Film Physics Division, Department of Physics, Chemistry, and Biology, IFM, Linköping University, SE-581 83 Linköping, Sweden
Dirk Rittrich
Affiliation:
Thin Film Physics Division, Department of Physics, Chemistry, and Biology, IFM, Linköping University, SE-581 83 Linköping, Sweden
Hans Högberg
Affiliation:
Thin Film Physics Division, Department of Physics, Chemistry, and Biology, IFM, Linköping University, SE-581 83 Linköping, Sweden
Lars Hultman
Affiliation:
Thin Film Physics Division, Department of Physics, Chemistry, and Biology, IFM, Linköping University, SE-581 83 Linköping, Sweden
*
a)Address all correspondence to this author. e-mail: [email protected]
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Abstract

We have investigated the electrical resistivity of (0001)-oriented Tin+1ACn (A = Si, Ge, Sn, n = 1–3) thin films deposited by magnetron sputtering onto Al2O3(0001) substrates at temperatures ranging from 500 to 950 °C. Four-point-probe measurements show that all films are good conductors with resistivity values of ∼21–51 μΩ cm for Ti–Si–C films, ∼15–50 μΩ cm for Ti–Ge–C films, and ∼46 μΩ cm for Ti2SnC. We find a general trend of decreasing resistivity with decreasing n for the Ti–Si–C and Ti–Ge–C systems due to the increased metallicity obtained with increasing density of A-element layers. We also show that crystalline quality and competitive growth of impurity phases affect the measured resistivity values. The effect of a given impurity phase largely depends on its location in the sample. Specifically, a TiCx layer in the center of the film constricts the current flow and results in an increased measured resistivity value. However, TiCx transition or seed layers at the substrate–film interface as well as surface segregation of Ge and Ti5Ge3Cx (for Ti–Ge–C) have only little effect on the measured resistivity values. For the Ti–Sn–C system, the resistivity is mainly influenced by the segregation of metallic Sn, yielding a wide spread in the measured values ranging from 20–46 μΩ cm, in the order of increased film purity.

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Articles
Copyright
Copyright © Materials Research Society 2007

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References

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