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Optics Express

Optics Express

  • Editor: Andrew M. Weiner
  • Vol. 21, Iss. 12 — Jun. 17, 2013
  • pp: 14131–14138

Effects of free electrons and quantum confinement in ultrathin ZnO films: a comparison between undoped and Al-doped ZnO

X.D. Li, T. P. Chen, P. Liu, Y. Liu, and K. C. Leong  »View Author Affiliations

Optics Express, Vol. 21, Issue 12, pp. 14131-14138 (2013)

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Band gaps and exciton binding energies of undoped and Al-doped ZnO thin films were determined from optical absorption measurement based on the Elliott’s exciton absorption theory. As compared to the undoped films, the doped films exhibit a band gap expansion and a reduction in the exciton binding energies due to the free electron screening effect, which suppresses the excitonic absorption and results in a blue shift of the absorption edge. The undoped and doped films show the same quantum size dependence, i.e. both the exciton binding energies and band gap energies increase with decreasing grain size of the oxides.

© 2013 OSA

OCIS Codes
(260.7190) Physical optics : Ultraviolet
(300.1030) Spectroscopy : Absorption
(310.6860) Thin films : Thin films, optical properties
(310.6188) Thin films : Spectral properties

ToC Category:
Thin Films

Original Manuscript: April 25, 2013
Revised Manuscript: May 23, 2013
Manuscript Accepted: May 23, 2013
Published: June 6, 2013

X.D. Li, T. P. Chen, P. Liu, Y. Liu, and K. C. Leong, "Effects of free electrons and quantum confinement in ultrathin ZnO films: a comparison between undoped and Al-doped ZnO," Opt. Express 21, 14131-14138 (2013)

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  1. S. J. Pearton, D. P. Norton, K. Ip, Y. W. Heo, and T. Steiner, “Recent progress in processing and properties of ZnO,” Prog. Mater. Sci.50(3), 293–340 (2005). [CrossRef]
  2. U. Özgür, Y. I. Alivov, C. Liu, A. Teke, M. A. Reshchikov, S. Dogan, V. Avrutin, S.-J. Cho, and H. Morkoc, “A comprehensive review of ZnO materials and devices,” J. Appl. Phys.98(4), 041301–041403 (2005). [CrossRef]
  3. T. Minami, “New n-type transparent conducting oxides,” MRS Bull.25(08), 38–44 (2000). [CrossRef]
  4. J. G. Gay, “Screening of excitons in semiconductors,” Phys. Rev. B4(8), 2567–2575 (1971). [CrossRef]
  5. D. C. Reynolds, D. C. Look, and B. Jogai, “Combined effects of screening and band gap renormalization on the energy of optical transitions in ZnO and GaN,” J. Appl. Phys.88(10), 5760–5763 (2000). [CrossRef]
  6. H. Fujiwara and M. Kondo, “Effects of carrier concentration on the dielectric function of ZnO:Ga and In2O3:Sn studied by spectroscopic ellipsometry: analysis of free-carrier and band-edge absorption,” Phys. Rev. B71(7), 075109–075118 (2005). [CrossRef]
  7. T. Makino, Y. Segawa, S. Yoshida, A. Tsukazaki, A. Ohtomo, M. Kawasaki, and H. Koinuma, “Free-carrier effects on zero- and one-phonon absorption onsets of n-type ZnO,” Jpn. J. Appl. Phys.44(10), 7275–7280 (2005). [CrossRef]
  8. B.-Z. Dong, G.-J. Fang, J.-F. Wang, W.-J. Guan, and X.-Z. Zhao, “Effect of thickness on structural, electrical, and optical properties of ZnO: Al films deposited by pulsed laser deposition,” J. Appl. Phys.101(3), 033713–033719 (2007). [CrossRef]
  9. J. C. Nie, J. Y. Yang, Y. Piao, H. Li, Y. Sun, Q. M. Xue, C. M. Xiong, R. F. Dou, and Q. Y. Tu, “Quantum confinement effect in ZnO thin films grown by pulsed laser deposition,” Appl. Phys. Lett.93(17), 173104 (2008). [CrossRef]
  10. L.-W. Wang and A. Zunger, “Dielectric constants of silicon quantum dots,” Phys. Rev. Lett.73(7), 1039–1042 (1994). [CrossRef] [PubMed]
  11. H. C. Weissker, J. Furthmuller, and F. Bechstedt, “Optical properties of Ge and Si nanocrystallites from ab initio calculations. II. hydrogenated nanocrystallites,” Phys. Rev. B65(15), 155328 (2002). [CrossRef]
  12. G. T. Einevoll, “Confinement of excitons in quantum dots,” Phys. Rev. B Condens. Matter45(7), 3410–3417 (1992). [CrossRef] [PubMed]
  13. S. Kishimoto, T. Yamada, K. Ikeda, H. Makino, and T. Yamamoto, “Effects of oxygen partial pressure on film growth and electrical properties of undoped ZnO films with thickness below 100 nm,” Surf. Coat. Tech.201(7), 4000–4003 (2006). [CrossRef]
  14. S. S. Kim and B.-T. Lee, “Effects of oxygen pressure on the growth of pulsed laser deposited ZnO films on Si(0 0 1),” Thin Solid Films446(2), 307–312 (2004). [CrossRef]
  15. S.-S. Lin and J.-L. Huang, “Effect of thickness on the structural and optical properties of ZnO films by r.f. magnetron sputtering,” Surf. Coat. Tech.185(2-3), 222–227 (2004). [CrossRef]
  16. S. Adachi, Optical Properties of Crystalline and Amorphous Semiconductors: Materials and Fundamental Principles (Kluwer Academic Publishers, 1999), Chap. 1.
  17. R. J. Elliott, “Intensity of optical absorption by excitons,” Phys. Rev.108(6), 1384–1389 (1957). [CrossRef]
  18. S. Ninomiya and S. Adachi, “Optical properties of cubic and hexagonal CdSe,” J. Appl. Phys.78(7), 4681–4689 (1995). [CrossRef]
  19. H. Yoshikawa and S. Adachi, “Optical constants of ZnO,” Jpn. J. Appl. Phys.36(Part 1, No. 10), 6237–6243 (1997). [CrossRef]
  20. I. Hamberg and C. G. Granqvist, “Evaporated Sn-doped In2O3 films: basic optical properties and applications to energy-efficient windows,” J. Appl. Phys.60(11), R123–R160 (1986). [CrossRef]
  21. R. Fausto, G. Guido, M. Oskar, and M. Elisa, “Theory of excitonic confinement in semiconductor quantum wires,” J. Phys. Condens. Matter11(31), 5969–5988 (1999). [CrossRef]
  22. H. Gotoh and H. Ando, “Excitonic quantum confinement effects and exciton electroabsorption in semiconductor thin quantum boxes,” J. Appl. Phys.82(4), 1667–1677 (1997). [CrossRef]

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