Preparation of wide optical spectrum and high antireflection MgF₂ thin film with SF₆ as reactive gas

Abstract

In order to suppress F-deficiency, SF 6 was added into the working gas Ar 2 as the reaction gas to deposit MgF 2 thin film on quartz glass substrate with radio frequency (RF) magnetron sputtering, and the effects of working pressure on the chemical compositions, microstructure and property of MgF 2 thin film were investigated. The results show that with the working pressure increase from 1.0 to 2.5 Pa, the atomic ratio of F: Mg decreased continuously, and reached 2.02 at 2.0 Pa, very close to the ideal stoichiometric ratio of 2:1; the crystallinity of MgF 2 film improved first then decreased, and finally changed into amorphous state; the particles' profile of MgF 2 film became clearer and their size increased significantly at first, but finally their profile became blurred. The refractive index of MgF 2 film decreased first and then increased, and got the lowest value at 2.0 Pa, 1.384, almost equal to that of MgF 2 bulk crystal. The transmittance of the coated glass within 300-1100 nm (hereinafter referred to as the transmittance of the thin film) increased first and then decreased. The transmittance of all films was higher than that of the bare glass substrate (93.2%), that is to say, all films had antireflection effect. The film transmittance reached 94.99% at 2.0 Pa, higher than that of the bare glass substrate by 1.79%, and higher than the simulated value calculated with G-Solver software by about 0.5%.

Effect of magnetron sputtering power on the properties of the AlO X monolayer and AlO X /MgF2 bilayer anti-reflection films

“…where the n 0 , n S , and n L are the refractive index of the air (1), the glass substrate (1.46), and the low-reflectivity material (1.385), respectively. Calculated from equation (1), the ideal refraction index n H = 1.667 [27] for the high refractive index film, which is close to that of the Al 2 O 3 film (1.62).…”

“…To prepare BLAR films with high transmittance in a wide wavelength range (300-1100 nm), we chose MgF 2 as the lowrefractive index material. MgF 2 is widely used as an antireflection film material because of its wide transparency interval of 0.11-6 µm and low refractive index of 1.38 [26], as well as its good anti-radiation and mechanical properties [27]. The thicknesses of the two films were fixed to their own λ 0 /4 to minimize the film's reflectivity, and the high refractive index film had to satisfy the following equation [15]:…”

Influence of pH on the Formation, Composition and Protectiveness of Fluoride Conversion Film Deposited on AZ31 Magnesium Alloy in KF Solution

“…The SEM and XPS depth distribution results show that thick films consisting of MgF 2 and KMgF 3 as the main constitutes are produced at pH 5 and 7.5, while pH 9 produces a thin film mainly composed of Mg(OH) 2 . Mg(OH) 2 weakens the protectiveness of fluoride film [40,41], while MgF 2 and KMgF 3 enhance its protectiveness [20-23, 30, 42, 43]. Therefore, the protectiveness of the film produced at pH 5 and 7.5 is better than that at pH 9.…”

“…Magnesium (Mg) and its alloys possess closer density (1.7-2.04 g/cm −3 ) and elastic modulus (41)(42)(43)(44)(45) to those of natural bone (1.8-2.1 g/cm −3 , 10-30 GPa), good biotissue compatibility and excellent cell adhesion. Additionally, they also demonstrate superior abilities to accelerate the osseointegration rate, enhance bone healing and prevent the biofilm formation [1][2][3][4].…”