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Surface Characterization of Ga-doped ZnO layers

Published online by Cambridge University Press:  05 April 2011

J.D. McNamara ,
J.D. Ferguson ,
M. Foussekis ,
I. Ruchala ,
M.A. Reshchikov ,
A.A. Baski ,
H. Liu ,
V. Avrutin  and
H. Morkoç
J.D. McNamara
Affiliation:
Department of Physics, Virginia Commonwealth University, Richmond, VA 23284
J.D. Ferguson
Affiliation:
Department of Physics, Virginia Commonwealth University, Richmond, VA 23284
M. Foussekis
Affiliation:
Department of Physics, Virginia Commonwealth University, Richmond, VA 23284
I. Ruchala
Affiliation:
Department of Physics, Virginia Commonwealth University, Richmond, VA 23284
M.A. Reshchikov
Affiliation:
Department of Physics, Virginia Commonwealth University, Richmond, VA 23284
A.A. Baski
Affiliation:
Department of Physics, Virginia Commonwealth University, Richmond, VA 23284
H. Liu
Affiliation:
Department of Electrical and Computer Engineering, VCU, Richmond, VA 23284
V. Avrutin
Affiliation:
Department of Electrical and Computer Engineering, VCU, Richmond, VA 23284
H. Morkoç
Affiliation:
Department of Electrical and Computer Engineering, VCU, Richmond, VA 23284
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Abstract

Epitaxial ZnO layers heavily doped with Ga (GZO) were grown at 400 °C under metaland oxygen-rich conditions in terms of metal-to-reactive oxygen ratio by plasma-assisted molecular beam epitaxy (MBE). Several atomic force microscopy (AFM) techniques were used to characterize the surface morphology and electrical properties of these GZO films in ambient conditions. Local I-V spectra indicate that layers grown under both O-rich and metal-rich conditions are highly resistive until a relatively high voltage sweep (±12 V) is used. After removal of an insulating surface layer, conduction is possible at lower voltages, but eventually the film resistivity increases and it again becomes insulating. In addition to local I-V spectra, local charge injection and subsequent surface potential measurements were used to probe surface charging characteristics. For charge injection experiments, a reverse-bias voltage is applied to the sample while scanning in contact mode with a metallized tip. The resultant change in surface potential due to trapped charge is subsequently observed using scanning Kelvin probe microscopy (SKPM). The layers deposited in a metal-rich environment demonstrate the expected behavior, but the O-rich layers show anomalous negative and positive charging. Finally, surface photovoltage (SPV) measurements using above-bandgap UV illumination were performed. The GZO layers produce SPV values of 0.4 to 0.5 eV, where the films deposited in an O-rich environment have slightly higher SPV values and faster restoration.

Keywords

transparent conductorscanning probe microscopy (SPM)morphology
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1315: Symposium MM – Transparent Conducting Oxides and Applications , 2011 , mrsf10-1315-mm06-25
Copyright
Copyright © Materials Research Society 2011

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References

REFERENCES

1. Bhosle, V., Prater, J.T., Yang, F., Burk, D., Forrest, S.R., and Narayan, J., J. Appl. Phys. 102, 023501 (2007).Google Scholar
2. Sato, H., Minami, T., Miyata, T., Takata, S., and Ishii, M., Thin Solid Films 246, 65–70 (1994).Google Scholar
3. Minami, T., Semicond. Sci. Technol. 20, S35–S44 (2005).Google Scholar
4. Avrutin, V., Liu, H.Y., Izyumskaya, N., Reshchikov, M.A., Özgür, Ü., Kvit, A.V., Voyles, P., and Morkoç, H., Mat. Res. Soc. Symp. Proc. 1201, H05–20 (2010).Google Scholar
5. Liu., H., Avrutin, V., Izyumskaya, N., Reshchikov, M.A., Özgür, Ü., and Morkoç, H., Phys. Stat. Sol.: RRL 4, (3–4) 70-72 (2010).Google Scholar
6. Kato, H., Sano, M., Miyamoto, K., and Yao, T., J. Cryst. Growth, 237-239, 538–543 (2002).Google Scholar
7. Moore, J.C., Reshchikov, M.A., Ortiz, J.E., Xie, J., Morkoç, H., and Baski, A.A., Proc. of SPIE 6894, 68940B–1 (2008).Google Scholar
8. Ferguson, J.D., Foussekis, M.A., Ruchala, M.D., Moore, J.C., Reshchikov, M.A., and Baski, A.A., Mat. Res. Soc. Symp. Proc. 1202, I04–01 (2010).Google Scholar
9. Kronik, L. and Shapira, Y., Surf. Sci. Rep. 37, 1–206 (1999).Google Scholar
10. Lagowski, J., Sproles, E.S. Jr., and Gatos, H.C., J. Appl. Phys. 48, 3566 (1977).Google Scholar
11. Foussekis, M.A., Baski, A.A., and Reshchikov, M.A., Mat. Res. Soc. Symp. Proc. 1109, B06–28 (2009)Google Scholar
12. Moore, J.C., Kenny, S.M., Baird, C.S., Morkoç, H., and Baski, A.A., J. Appl. Phys. 105, 116102 (2009).Google Scholar
13. Foussekis, M., Baski, A. A., and Reshchikov, M. A., Appl. Phys. Lett. 94, 162116 (2009).Google Scholar
14. Reshchikov, M. A., Foussekis, M., and Baski, A. A., J. Appl. Phys. 107, 113434 (2010).Google Scholar