Optical characteristics of the novel nanosized thin ZnGa2S4 films sprayed at different deposition times: Determination of optical band-gap energy using different methods

This article has been allocated to studying microstructural features and optical properties of the novel sprayed polycrystalline thin ZnGa2S4 films. These novel films have been deposited on microscopic soda lime glass substrates at different deposition times (5, 10, 15, 20 min). The crystal structure, crystallinity degree and crystalline volume fraction have been studied using X-ray diffractograms. The stoichiometry of ZnGa2S4 films has been checked using energy dispersive X-ray analysis. The field-emission-scanning-electron microscope, SEM has been utilized to investigate the particle size and surface morphology of films. SEM micrographs showed that the particle size of these films increased from 21.231 nm to 75.569 nm as deposition time increased. Optical properties have been studied employing transmittance and reflectance spectra in the range 300-2500 nm. Very important optical parameters such as absorption coefficient, skin depth, Urbach energy, steepness parameters, and electron-phonon interactions have been extensively studied. The direct and indirect gap energy have been investigated by different models and compared with Tauc's model. The optical band gap energy values slightly decrease from 4.10 to 3.70 eV as the deposition time increases. The hot-probe experiment validates our films' propensity for acting as n-type semiconductors. The current findings recommend using these films in many Photovoltaic applications as a window layer.

Automated summary

This article investigates the microstructural features and optical properties of novel sprayed polycrystalline thin ZnGa2S4 films. The films were deposited on soda lime glass substrates for different deposition times and their crystal structure, crystallinity degree, and crystalline volume fraction were analyzed. The SEM analysis revealed an increase in particle size with longer deposition times. The optical properties were studied in terms of transmittance, reflectance, and various optical parameters, with the energy gap decreasing as the deposition time increased. The films were found to be n-type semiconductors and suitable for photovoltaic applications.