A Study on the Transmittance, Heat-Resistance, and Mechanical Properties of SiO₂, TiO₂ Anti-Reflective Single Layers Deposited on Sapphire Substrate by MOCVD

Abstract

To improve sensing capability of infrared, heat-resistance and mechanical properties, the SiO 2 and TiO 2 antireflective layers were coated on sapphire substrate by MOCVD. The standard wavelength was 4,600nm, and the thickness of anti-reflective layers were 379 and 758nm in case of λ/4 and λ/2 of incident angle(65˚), respectively.The SiO 2 and TiO 2 anti-reflective layers were coated 12.6 and 9.7nm/min of deposition rates by increasing oxygen pressure to set the ideal refractive index of 1.283. In case of SiO 2 (λ/2) coating, the transmittance increased from 55.0 to 62.7%. The transmittance of TiO 2 (λ/2) anti-reflective layer also increased from 55.0 to 64.8%. The flexural strength of SiO 2 (λ/2) and TiO 2 (λ/2) layer coated sapphire increased from 337.8 to 362.9 and 371.8MPa, respectively. The flexural strength at 500℃ of these materials also increased respectively to 304.5, 358.2MPa from 265.9MPa. From these results, we confirmed these materials can be used as transmission window of infrared light.