RT journal article
T1 Optical Characterization of H-Free a-Si Layers Grown by rf-Magnetron Sputtering by Inverse Synthesis Using Matlab: Tauc–Lorentz–Urbach Parameterization
A1 Márquez Navarro, Emilio José
A1 Ruiz Pérez, Juan José
A1 Ballester, Manuel
A1 Márquez Lozano, Almudena del Pilar
A1 Blanco Ollero, Eduardo
A1 Minkov, Dorian
A1 Fernández Ruano, Susana M.
A1 Saugar, Elias
A2 Física de la Materia Condensada
A2 Matemáticas
K1 amorphous semiconductors
K1 optical properties
K1 dielectric function
K1 thin-filmcharacterization
K1 Tauc–Lorentz model
K1 Tauc–Lorentz–Urbach model
AB Several, nearly-1-mu m-thick, pure, unhydrogenated amorphous-silicon (a-Si) thin layers were grown at high rates by non-equilibrium rf-magnetron Ar-plasma sputtering (RFMS) onto room-temperature low-cost glass substrates. A new approach is employed for the optical characterization of the thin-layer samples, which is based on some new formulae for the normal-incidence transmission of such a samples and on the adoption of the inverse-synthesis method, by using a devised Matlab GUI environment. The so-far existing limiting value of the thickness-non-uniformity parameter, & UDelta;d, when optically characterizing wedge-shaped layers, has been suppressed with the introduction of the appropriate corrections in the expression of transmittance. The optical responses of the H-free RFMS-a-Si thin films investigated, were successfully parameterized using a single, Kramers-Kronig (KK)-consistent, Tauc-Lorentz oscillator model, with the inclusion in the model of the Urbach tail (TLUC), in the present case of non-hydrogenated a-Si films. We have also employed the Wemple-DiDomenico (WDD) single-oscillator model to calculate the two WDD dispersion parameters, dispersion energy, Ed, and oscillator energy, Eso. The amorphous-to-crystalline mass-density ratio in the expression for Ed suggested by Wemple and DiDomenico is the key factor in understanding the refractive index behavior of the a-Si layers under study. The value of the porosity for the specific rf-magnetron sputtering deposition conditions employed in this work, with an Ar-pressure of ~4.4 Pa, is found to be approximately 21%. Additionally, it must be concluded that the adopted TLUC parameterization is highly accurate for the evaluation of the UV/visible/NIR transmittance measurements, on the H-free a-Si investigated. Finally, the performed experiments are needed to have more confidence of quick and accurate optical-characterizations techniques, in order to find new applications of a-Si layers in optics and optoelectronics.
PB MDPI
SN 2079-6412
YR 2021
FD 2021-11
LK http://hdl.handle.net/10498/26215
UL http://hdl.handle.net/10498/26215
LA eng
NO Funding This research was funded by the SCALED project, grant number PID2019-109215RB-C42, provided by the Spanish Ministry of Science and Innovation.
DS Repositorio Institucional de la Universidad de Cádiz
RD 11-nov-2026