A study on the evolution of dielectric function of ZnO thin films with decreasing film thickness

• Main Authors: Li, X. D., Chen, T. P., Liu, P., Liu, Y., Liu, Z., Leong, K. C.
• Other Authors: School of Electrical and Electronic Engineering
• Format: Article
• Language: English
• Published: 2014
• Subjects: DRNTU::Engineering::Electrical and electronic engineering
• Online Access: https://hdl.handle.net/10356/104196; http://hdl.handle.net/10220/19570
• Institution: Nanyang Technological University

Dielectric function, band gap, and exciton binding energies of ultrathin ZnO films as a function of film thickness have been obtained with spectroscopic ellipsometry. As the film thickness decreases, both real (ε1 ) and imaginary (ε2 ) parts of the dielectric function decrease significantly, and ε2shows a blue shift. The film thickness dependence of the dielectric function is shown related to the changes in the interband absorption, discrete-exciton absorption, and continuum-exciton absorption, which can be attributed to the quantum confinement effect on both the band gap and exciton binding energies.