We report on the optical bandgap engineering of sputtered hydrogenated amorphous silicon carbide (a-SiC:H) thin films under different hydrogen dilution conditions during the deposition process and after post-deposition annealing treatments. The Tauc-gap and Urbach energy are calculated from ultraviolet-visible optical transmittance measurements. Additionally, the effect of the thermal annealing temperature on the hydrogen out-diffusion is assessed through infra-red absorption spectroscopy. A new model for the optical absorption of amorphous semiconductors is presented and employed to determine the bandgap as well as the Urbach energy from a single fit of the absorption coefficient. This model allowed the discrimination of the Urbach tail from the Tauc region without any external bias. Finally, the effect of the hydrogen dilution on the band-edge and the Urbach focus is discussed.

This research was funded by the Research Management Office (DGI) of the Pontificia Universidad Católica del Perú (PUCP). The authors have been supported by the PUCP under the PhD scholarship program Huiracocha (J A Guerra) and by the National Council of Science and Technology (CONCYTEC) under the scholarships granted to the PUCP (J R Angulo and J Llamoza). The author would like to thank Prof Dr H P Strunk, F Benz and Dr Y Weng of the University of Stuttgart for the TEM measurements.

The complex refractive indices of formamidinium cesium lead mixed-halide [FA0.83Cs0.17Pb(I1– xBrx)3] perovskite thin films of compositions ranging from x = 0 to 0.4, with both flat and wrinkle-textured surface topographies, are reported. The films are characterized using a combination of variable angle spectroscopic ellipsometry and spectral transmittance in the wavelength range of 190 nm to 850 nm. Optical constants, film thicknesses and roughness layers are obtained point-by-point by minimizing a global error function, without using optical dispersion models, and including topographical information supplied by a laser confocal microscope.

The complex refractive indices of formamidinium cesium lead mixed-halide [FA0.83Cs0.17Pb(I1– xBrx)3] perovskite thin films of compositions ranging from x = 0 to 0.4, with both flat and wrinkle-textured surface topographies, are reported. The films are characterized using a combination of variable angle spectroscopic ellipsometry and spectral transmittance in the wavelength range of 190 nm to 850 nm.

To obtain an adequate luminescent emission, a significant effort must be made to find a suitable host material. An interesting and highly efficient method is a combinatorial approach, which allows high velocity screening of a wider range of properties. In the present work, a compositional gradient-based, thin-film library of -AlOxNy:Yb3+ has been prepared by radio frequency co-sputtering from two targets. The ytterbium concentration range spreads from 0.9 to 4.2 at. % and the oxygen to nitrogen ratio from 0.6 to 3.6. Using different annealing temperatures, the activation energy of the rare earth ions and activation mechanisms can be evaluated. Finally, optimal elemental compositions in the investigated range are proposed.

This work was supported by the Peruvian science foundation CIENCIACTIVA of CONCYTEC and DAAD-CONCYTEC project (2017–2019). The Research Management Office (DGI) of the the Pontificia Universidad Católica del Perú (PUCP) project 492-2017. The research activity was performed in the framework of the doctoral scholarship of L. F. Flores under the contract number 236-2015-FONDECYT. The authors are also thankful to the Center of Materials Characterization (CAM) and the Institute of Corrosion and Protection (ICP) of the PUCP for the EDX, PL and FTIR measurements.