Transmittance enhancement of micro-grating structure sapphire with high-refractive index Y2O3 layer

The theoretical analysis of micro-grating structure sapphire (sapphire MGS) with Y₂O₃ layer using the finite-difference time-domain method is presented. The results show that the total transmittance and reflectance of Y₂O₃/sapphire MGS have a close relationship with the thickness of Y₂O₃ layer, where about 300 nm is the ideal thickness. According to the simulant results, 300 and 600 nm of thicknesses of Y₂O₃ layer deposited onto sapphire MGS substrate by reactive magnetron sputtering method are studied experimentally. The experimental results agree well with the calculated data and further have better optical properties because of the rough surface of Y₂O₃ layer. It illustrates that the 300-nm Y₂O₃/sapphire MGS exhibits the best increase in the total transmittance and diffuse transmittance due to the greater graded refractive index profile than sapphire MGS. The results of this paper have potential applications in solar cells and diffraction grating.