Abstract
GaN films were grown using SiN treatment of sapphire substrate by metalorganic vapor-phase epitaxy in a home-made vertical reactor at atmospheric pressure. The growth was interrupted at different stages to investigate the impact of interface and surface roughness on the optical properties of the GaN layers. A transition from a three-dimensional (3D) to two-dimensional (2D) growth mode was revealed by real-time in situ laser reflectometry (λ = 632.8 nm) as well as by atomic force microscopy images. A theoretical model is proposed to determine the refractive index evolution during GaN layer growth based on the Bruggeman effective medium approximation. Ex situ multiwavelength reflectivity signals were fit to the thin-film interference equations to derive the evolution of the effective refractive indexes for the surface and interface GaN layer, thereby determining the refractive index of the GaN layer during growth. Ex situ spectroscopic ellipsometry measurements of the GaN layer refractive indexes at different growth stages were compared with calculated results. Moreover, an empirical law was developed to fit the refractive index evolution during GaN layer growth and used for in situ reflectivity signal simulation in order to deduce the growth rate. Finally, good agreement was observed between the experimental and theoretical findings.
Similar content being viewed by others
References
F.A. Ponce and D.P. Bour, Nature (London) 386, 351 (1997).
S. Nakamura, T. Mukai, and M. Senoh, Appl. Phys. Lett. 64, 1687 (1994).
S. Nakamura, M. Senoh, S. Nagahama, N. Iwasa, T. Yamada, T. Matsushita, H. Kiyoku, Y. Sugimoto, T. Kozaki, H. Umemoto, M. Sano, and K. Chocho, Jpn. J. Appl. Phys. 37, L1020 (1998).
J.C. Carrano, T. Li, P.A. Grudowski, C.J. Eiting, R.D. Dupuis, and J.C. Campbell, J. Appl. Phys. 83, 6148 (1998).
D.B. Kushev, N.N. Zheleva, Y. Demakopoulou, and D. Siapkas, Infrared Phys. 26, 386 (1986).
E. Marquez, J.M. Gonzalez-Leal, R. Pricto-Alcon, M. Vleek, A. Stronski, and T. Wagner, et al., Appl. Phys. A 67, 371 (1988).
D.A. Minkov, J. Phys. D 22, 1157 (1989).
J.C. Martinez-Anton and E. Bernabeu, Thin Solid Films 85, 313 (1998).
T. Gungor and B. Saka, Thin Solid Films 467, 319 (2004).
G. Leveque and Y. Villachon-Renard, Appl. Opt. 29, 3207 (1990).
A.B. Djurisic, T. Fritz, and K. Leo, Opt. Commun. 166, 35 (1999).
Z. Benzarti, I. Halidou, T. Boufaden, B. El Jani, S. Juillaguet, and M. Ramonda, Phys. Status Solidi A 201, 502 (2004).
I. Halidou, Z. Benzarti, T. Boufaden, B. El Jani, S. Juillaguet, and M. Ramonda, Mater. Sci. Eng. B 110, 251 (2004).
I. Halidou, Z. Benzarti, H. Fitouri, W. Fathallah, and B. El Jani, Phys. Status Solidi C 4, 129 (2007).
A. Bechtenia, A. Touré, T.A. Lafford, Z. Benzarti, I. Halidou, M.M. Habchi, and B. El Jani, J. Cryst. Growth 308, 283 (2007).
I. Halidou, Z. Benzarti, Z. Bougrioua, T. Boufaden, and B. El Jani, Superlattices Microstruct. 40, 490 (2006).
A. Laycuras, M.G. Lee, and A. Haussmann, J. Appl. Phys. 78, 5680 (1995).
D.E. Aspnes and J.B. Theeten, Phys. Rev. B 20, 3292 (1979).
H.G. Tompkins and E.A. Irene, Handbook of Ellipsometry (Norwich, NY: William Andrew, 2005).
D.E. Aspnes, Phys. Rev. B 41, 10334 (1990).
I. Halidou, A. Touré, A. Fouzri, M. Ramonda, and B. El Jani, Appl. Surf. Sci. 20, 660 (2013).
W.G. Breiland and K.P. Killen, J. Appl. Phys. 78, 6726 (1995).
L.I. Epstein, J. Opt. Soc. Am. 42, 806 (1952).
A. Thelen, J. Opt. Soc. Am. 56, 1533 (1952).
P.S. Hauge, J. Opt. Soc. Am. 69, 1143 (1979).
F.K. Urban III and M.F. Tabet, J. Vac. Sci. Technol. A 11, 976 (1993).
H. Fitouri, Z. Benzarti, I. Halidou, T. Boufaden, and B. El Jani, Phys. Status Solidi A 202, 2467 (2005).
G. Yu, H. Ishikawa, M. Umeno, T. Egawa, and J. Watanabe, et al., Appl. Phys. Lett. 72, 2202 (1998).
Ch. Liu and I.M. Watson, Semicond. Sci. Technol. 22, 629 (2007).
C. Liu, S. Stepanov, A. Gott, P.A. Shields, E. Zhirnov, W.N. Wang, E. Steimetz, and J.T. Zettler, Phys. Status Solidi C 3, 1884 (2006).
Acknowledgements
The authors would like to thank Dr. A. Rebey, and Dr. A. Khalfallah for helpful discussions. This work is supported by DGRST.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Benzarti, Z., Khelifi, M., Halidou, I. et al. Study of Surface and Interface Roughness of GaN-Based Films Using Spectral Reflectance Measurements. J. Electron. Mater. 44, 3243–3252 (2015). https://doi.org/10.1007/s11664-015-3855-9
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11664-015-3855-9