Hostname: page-component-586b7cd67f-tf8b9 Total loading time: 0 Render date: 2024-11-22T16:42:00.677Z Has data issue: false hasContentIssue false

Emergence of blue emission with decreasing film thickness and grain size for ZnO grown via thermal oxidation of Zn-metal films

Published online by Cambridge University Press:  14 February 2012

L.R. Covington
Affiliation:
Department of Chemistry and Physics, Coastal Carolina University, Conway, SC 29528, U.S.A
R. Stansell
Affiliation:
Department of Chemistry and Physics, Coastal Carolina University, Conway, SC 29528, U.S.A
J.C. Moore*
Affiliation:
Department of Chemistry and Physics, Coastal Carolina University, Conway, SC 29528, U.S.A
*
*Corresponding author, email: [email protected], phone: 843-349-2985
Get access

Abstract

We have investigated the photoluminescence properties of ZnO grown on sapphire substrates via the thermal oxidation of Zn-metal films at various temperatures and thicknesses. X-ray diffraction (XRD) spectra indicate that the resulting films possess a polycrystalline hexagonal wurtzite structure without preferred orientation. For films having a thickness of 200 nm, crystal grain size was observed to decrease with increasing annealing temperature up to 600ºC, and then increase at higher temperatures. Thicker films demonstrated a modest increase in grain size as temperature increased from 300ºC to 1200ºC. The influence of film thickness on the optical properties was investigated using room temperature photoluminescence (PL). Specifically, PL spectra indicate four emission bands: excitonic ultraviolet, blue, and deep-level green and yellow emission. The strongest UV emission and narrowest full width at half maximum (0.09 eV) was observed for films having a thickness of 200 nm and annealed at low temperature (300ºC). As film thickness decreased, we observed the emergence of blue emission. The emergence of blue emission when depletion width grows relative to the bulk suggests that the origin of the blue emission is related to the negatively charged Zinc interstitials found within the deletion region near the interface.

Type
Research Article
Copyright
Copyright © Materials Research Society 2012

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. Özgür, U., Alivov, Y.I., Liu, C., Teke, A., Reshchikov, M.A., Dogan, S., Avrutin, V., Cho, S.J., and Morkoç, H., J. Appl. Phys. 98, 041301 (2005).Google Scholar
2. Moore, J.C., Kenny, S.M., Baird, C.S., Morkoç, H., Baski, A.A., J. Appl. Phys. 105, 116102 (2009).Google Scholar
3. Chevtchenko, S., Moore, J.C., Özgür, Ü., Gu, X., Nemeth, B., Nause, J.E., Baski, A.A., Morkoç, H., Appl. Phys. Lett., 89, 182111 (2006).Google Scholar
4. Cho, S., Ma, J., Kim, Y., Sun, Y., Wong, G., and Ketterson, J., Appl. Phys. Lett. 75(18), 2761 (1999).Google Scholar
5. Wu, X., Siu, G., Fu, C., and Ong, H., Appl. Phys. Lett. 78, 2285 (2001).Google Scholar
6. Wanga, Z., Zu, X., Zhu, S., and Wang, L., Physica E 35(1), 199202 (2006).Google Scholar
7. Fu, Z., Guo, C., Lin, B., and Liao, G., Chin. Phys. Lett. 15(6), 457459 (1998).Google Scholar
8. Zhang, D., Xue, Z., and Wang, Q., J. Phys. D 35, 2837 (2002).Google Scholar
9. Zhao, L., Lian, J. S., Liu, Y. H., and Jiang, Q., Transactions of Nonferrous Metals Society of China 18(1), 145149 (2008).Google Scholar
10. Zhao, J., Hu, L., Wang, Z., Zhao, Y., Liang, X., and Wang, M., Appl. Surf. Sci. 229(1-4), 311315 (2004).Google Scholar
11. Fujihara, S., Ogawa, Y., and Kasai, A., Chem. Mater. 16(2965) (2004).Google Scholar
12. Wang, Y., Lau, S., Lee, H., Yu, S., Tay, B., Zhang, X., and Hng, H., J. Appl. Phys. 94, 354 (2003).Google Scholar
13. Chen, S., Liu, Y., Zhao, J. M, D., Zhi, Z., Lu, Y., Zhang, J., Shen, D., and Fan, X., J. Cryst. Growth 240(3-4), 467472 (2002).Google Scholar
14. Lee, M. and Tu, H., Jap. J. Appl. Phys. 47(2), 980982 (2008).Google Scholar
15. Moore, J.C., Covington, L.R., Foster, R.L., Gee, E.J., Jones, M.R., Morris, S.A., Proc. of SPIE, 7940, 79401L (2011).Google Scholar
16. Avrutin, V., Özgür, Ü., Izyumskaya, N., Chevtchenko, S., Leach, J., Moore, J.C., Baski, A.A., Litton, C., Everitt, H.O., Tsen, K.T., Abouzaid, M., Ruterana, P., and Morkoç, H., Proc. of SPIE 6474, 64741M (2007).Google Scholar
17. Avrutin, V., Özgür, Ü., Izyumskaya, N., Chevtchenko, S., Leach, J., Moore, J.C., Baski, A.A., Everitt, H.O., Tsen, K.T., Ruterana, P., Morkoç, H., Mater. Res. Soc. Symp. Proc., 963E (2006).Google Scholar
18. Moore, J.C., Skrobiszewski, J.L, Baski, A.A.. J. Vac. Sci. Technol. 25, 4, 812-815 (2007).Google Scholar
19. Gupta, R., Shridhar, N., and Katiyar, M., Mater. Sci. Semi. Proc. 5, 11 (2002).Google Scholar
20. Tauc, J., Mater. Res. Bulletin 3(1), 3746 (1968).Google Scholar
21. Jain, A., Sagar, P., and Mehra, R. M., Mater. Sci. Pol. 25(1), 233242 (2007).Google Scholar
22. van Dijken, A., Meulenkamp, E., Vanmaekelbergh, D., and Meijerink, A., J. Lumin. 90, 123128 (2000).Google Scholar