Hostname: page-component-586b7cd67f-g8jcs Total loading time: 0 Render date: 2024-11-27T00:35:11.606Z Has data issue: false hasContentIssue false

Mobility in SnO2:F Thin Polycrystalline Films: Grain Boundary Effect and Scattering in the Grain Bulk

Published online by Cambridge University Press:  21 March 2011

A. S. Gilmore
Affiliation:
Colorado School of Mines, Golden, Colorado 80401, USA
A. Al-Kaoud
Affiliation:
Colorado School of Mines, Golden, Colorado 80401, USA
V. Kaydanov
Affiliation:
Colorado School of Mines, Golden, Colorado 80401, USA
T.R. Ohno
Affiliation:
Colorado School of Mines, Golden, Colorado 80401, USA
Get access

Abstract

Basic electronic properties relevant to the carrier mobility were studied in tin oxide thin films doped with fluorine, prepared by atmospheric pressure chemical vapor deposition. Electrical resistivity, Hall and Seebeck effects, plasma and collision frequencies were measured (the last two by using multiangle spectral ellipsometry) and analyzed for films with carrier concentrations from 1.8×1020 to 5.6×1020 cm−3. Scanning over the sample area of resistivity (four-point probe method) and Seebeck coefficient (thermoprobe) monitored uniformity of electronic properties in plane. Ellipsometry was used to check uniformity over the film thickness. Films with a thickness above 400 nm demonstrated high spatial uniformity and were used for further studies.

Effective mass was determined from combined Hall and plasma frequency measurements and was found to be independent of carrier concentration, which indicates a parabolic band spectrum. Its value was very close to the literature data. In films with carrier concentration ≥3×1020 cm−3 the Hall mobility was very close to the optical mobility calculated based on collision frequency and effective mass values. This indicates a very small contribution of grain boundaries to the total resistivity of films. Thus the measured mobility is close to the electron mobility in the grain bulk.

The scattering parameter value derived from thermopower measurements along with the temperature independent mobility indicated that electron scattering by impurity ions screened by free carriers is the dominating scattering mechanism. Theoretical estimates of mobility are very close to the highest measured mobility values (≥ 30 cm2/Vs) if the spatial dispersion of the dielectric constant is taken into account. Comparison of differently processed films showed that compensation of donor dopant with uncontrolled acceptor centers significantly impacted mobility.

Type
Research Article
Copyright
Copyright © Materials Research Society 2001

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1. Haacke, G., J. Appl. Phys. 47, (1976), 4086.Google Scholar
2. Madelung, O., Semiconductors other than Group IV Elements and III-V Compounds, Springer-Verlag, Berlin-Heidelberg, New York 1992.Google Scholar
3. Kolodziejchak, J. and Sosnovski, L., Acta Phys. Polon. 21 (1962), 399.Google Scholar
4. Askerov, B. M., Electron Transport Phenomena in Semiconductors, World Scientific, Singapore, 1994.Google Scholar
5. Young, D.L., Coutts, T.J., Kaydanov, V.I., Mulligan, W.R., J. Vac. Sci. Technol. A18, 1 (2000)Google Scholar
6. Coutts, T.J., Young, D.L., and Li, X., MRS Bulletin 25, No. 8, 58 (2000)Google Scholar
7. Woods, L.M., Levi, D.H., Kaydanov, V., Robinson, G.Y., and Ahrenkiel, R.K., Proceedings of the2nd World Conf. on Photovoltaic Solar Energy Conversion, July 6-10, 1998, Vienna, Austria, 1043.Google Scholar
8. Brooks, H., Advances in Electronics and Electron. Phys. 7, (1955), 87.Google Scholar
9. Mansfield, R., Proc. Phys. Soc. B, 69, (1956), 79.Google Scholar