HfO2/SiO2 anti-reflection films for UV lasers via plasma-enhanced atomic layer deposition

The laser-induced damage threshold (LIDT) of HfO 2 /SiO 2 anti-reflection (AR) films for ultraviolet (UV) lasers was improved via low-temperature plasma-enhanced atomic layer deposition (PEALD). Focused on the chemical composition, optical absorption, surface scattering, and laser-resistance, the impact of precursor exposure time on PEALD SiO 2 film properties and growth temperature on PEALD SiO 2 and HfO 2 film properties were investigated respectively. When irradiated by UV laser, PEALD SiO 2 film exhibits a higher LIDT than the PEALD HfO 2 film, which is consistent with their less impurity content and lower absorption. A bilayer structure HfO 2 /SiO 2 AR film for 355 nm laser was designed and experimentally demonstrated via PEALD growth at a temperature of 150 °C. The prepared PEALD AR film shows a reflectance <0.2% at 355 nm as designed and better laser-damage resistance with a LIDT of 24.4 J/cm 2 (355 nm, 7.8 ns) than the conventional e-beam deposition method. • The HfO 2 /SiO 2 anti-reflection film for UV laser was presented via low-temperature PEALD. • The presented PEALD AR film shows better laser-damage resistance than conventional e-beam deposition method. • The impact of precursor exposure time on PEALD film properties were investigated. • The XPS measurement shows the impurity content of PEALD HfO 2 film is high, leading to a large absorption and low LIDT.