Ion beam assisted electron beam vacuum deposition of antireflective SiO2 coating on MgAl2O4 spinel

In this paper, the electron beam vacuum coating method was used to coat a SiO2 film on an MgAl2O4 spinel substrate. The thickness of the coating was aimed to be 925 nm based on the physics of the antireflection coatings. Atomic force microscope images revealed that the coated silica was 880 nm thick, which is close to the aimed theoretical thickness and had 2.11 nm roughness. It could enhance the transparency of the spinel substrate by being coated on it. The infrared transmittance of the sample coated with SiO2 film in the range of 3700 nm-4800 nm was measured by a Fourier transform infrared spectrometer and reached 92.5% to 78.5%, which was about 2%-4% higher than that of MgAl2O4 spinel. In addition, it was discovered that the bonding force between the coating and the substrate is determined to be about 200 MPa. The results of this study can be used for further precise design and production of antireflection coatings on the transparent materials that need more transparency.

Automated summary

In this study, the electron beam vacuum coating method was used to coat a SiO2 film on an MgAl2O4 spinel substrate. The coated silica had a thickness of 880 nm, close to the aimed theoretical thickness, and a roughness of 2.11 nm. It significantly enhanced the transparency of the spinel substrate. The infrared transmittance of the coated sample was measured to be 92.5% to 78.5% in the range of 3700 nm-4800 nm, showing an improvement of 2%-4% compared to the MgAl2O4 spinel. The bonding force between the coating and the substrate was determined to be about 200 MPa. These findings are important for the precise design and production of antireflection coatings on transparent materials.