Application of the Holomorphic Tauc-Lorentz-Urbach Function to Extract the Optical Constants of Amorphous Semiconductor Thin Films

The Tauc–Lorentz–Urbach (TLU) dispersion model allows us to build a dielectric function from only few parameters. However, this is non-analytic and presents some mathematical drawbacks. As consequence of issue, the becomes inaccurate. In present work, we will adopt procedure conveniently transform TLU into self-consistent model. transformation involves integration original imaginary ϵ2 by using Lorentzian-type semi-width, Γ. This novel analytic obeys other necessary requirements optical constants solid-state materials. main difference with occurs at values photon energy near or lower than that bandgap (within Urbach absorption region). particular, new reliably extend characterization amorphous-semiconductor thin films within limit zero energy. To best our knowledge, first time has been successfully used accurately determine unhydrogenated a-Si their normal-incidence transmission spectra.