Using a Lorentz–Drude model, we determine optical constants in the range from 300 to 1000 nm for CdIn<sub>2</sub>O<sub>4</sub> thin films deposited by rf reactive sputtering from the measurement of transmission and reflection. We discuss the effect of deposition conditions including substrate temperature and oxygen concentration in a reactive atmosphere and postdeposition heat treatment on optical constants, absorption properties, and the bandgap of thin films. It can be found that changes in optical constants and bandgap are in good agreement with those of the carrier concentration. Therefore an optical constant could be related to the film’s inherent properties, such as the energy gap and carrier concentration, and might be regarded as a useful probe for monitoring <i>in situ</i> the film process. A study of Urbach tails reveals that the effect of substrate temperature on the characteristic photon energy is negligible.
© 2001 Optical Society of America
Bin Li, Ling Zeng, Fengshan Zhang, and Junpin Zhang, "Effect of Deposition Conditions and Postdeposition Heat Treatment on the Optical Properties of CdIn2O4 Thin Films," Appl. Opt. 40, 6312-6318 (2001)