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Structural, Optical, and Electron Transport Qualities of Zinc-Stannate Thin Films

Published online by Cambridge University Press:  21 March 2011

David L. Young ,
Timothy J. Coutts  and
Don L. Williamson
David L. Young
Affiliation:
National Renewable Energy Laboratory, Golden, CO 80401, U.S.A.
Timothy J. Coutts
Affiliation:
National Renewable Energy Laboratory, Golden, CO 80401, U.S.A.
Don L. Williamson
Affiliation:
Colorado School of Mines, Golden, CO 80401, U.S.A.
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Abstract

Single-phase, spinel zinc stannate (ZTO = Zn2SnO4) thin films were grown by rf magnetron sputtering onto glass substrates. Uniaxially oriented films with resistivities of 10−2 -10−3 ωcm, mobilities of 16 - 26 cm2/V-s, and n-type carrier concentrations in the low 1019 cm−3 range were achieved. X-ray diffraction peak intensity studies established the films to be in the inverse spinel configuration. 119Sn Mössbauer studies identified two octahedral Sn sites, each with a unique quadrupole splitting, but with a common isomer shift consistent with Sn+4. A pronounced Burstein-Moss shift moved the optical bandgap from 3.35 eV to as high as 3.89 eV.

Density-of-states effective mass, relaxation time, mobility, Fermi energy level, and a scattering parameter were calculated from transport data. Effective-mass values increased with carrier concentration from 0.16 to 0.26 me as the Fermi energy increased from 0.2 to 0.9 eV above the conduction-band minimum. First-order nonparabolic conduction-band theory was applied to extrapolate a bottom-of-the-band effective mass of 0.15 me. Calculated scattering parameters and temperature-dependent transport measurements correlated well with ionized impurity scattering with screening by free electrons for highly degenerate films.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 666: Symposium F – Transport and Microstructural Phenomena , 2001 , F3.8
Copyright
Copyright © Materials Research Society 2001

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References

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