Optical properties of magnesium fluoride thin films produced by argon ion-beam assisted deposition

Abstract

Magnesium fluoride thin films were deposited on silica glass and single crystal silicon substrates by argon ion-beam assisted deposition (IBAD). The effects of argon ions impinging on the growing film on the optical and chemical properties of the single layers were investigated. Compared to MgF2 films produced by direct electron-beam evaporation, the films obtained by IBAD exhibited increased optical absorption and refractive indices, fluorine depletion and increased oxygen contamination. Optical data were analyzed and are discussed with regard to the chemical composition of the films.

On Optical Properties of Dilute Colloidal Gold

“…F color center is formed from a vacancy and an electron trapped in the vacancy. The Smakula' s formula has been utilized also in the case of magnesium fluoride thin films containing simultaneously F color centers and small metal particles [23]. In the study [23], the authors utilized the Bruggeman effective medium model.…”

“…The Smakula' s formula has been utilized also in the case of magnesium fluoride thin films containing simultaneously F color centers and small metal particles [23]. In the study [23], the authors utilized the Bruggeman effective medium model. Here, the approach is different from [23] because there are no color centers but only metal NPs which we treat qualitatively as "color centers."…”

“…In the study [23], the authors utilized the Bruggeman effective medium model. Here, the approach is different from [23] because there are no color centers but only metal NPs which we treat qualitatively as "color centers." It has been proposed in the literature that a Lorentz line [8] or a sum of Lorentz lines [24] can be used for the description of light absorption band of gold colloid.…”

Absolute Absorption Measurements in Optical Coatings by Laser Induced Deflection

“…Nonstoichiometric films often give rise to increased absorption due to the formation of intrinsic defects. For oxide coatings these are preferable oxygen vacancies [12][13][14] whereas for fluorides the formation of color centers or even localized metallic clusters is critical [15,16]. For our studies, high-reflecting (HR) mirrors (MgF 2 /LaF 3 ) for 193 nm and AOI = 45 • have been deposited onto CaF 2 substrates (1" diameter, thickness 2 mm) by thermal evaporation using deposition temperatures in the range 250-370 • C. Absorption measurements have been carried out by means of the thin disc vertical concept using an ArF excimer laser (ExciStar S Industrial, Coherent GmbH, Goettingen, Germany) with a repetition rate f = 1 kHz.…”

Bilayer SiO2 Nanorod Arrays as Omnidirectional and Thermally Stable Antireflective Coating

“…A thin layer of η 1 on front surface helps in eliminating the reflectance to create destructive interference from the reflected light at air-coating and coating-substrate interface. [4,9] MgF 2 thin films having a thickness of 137.5 nm reflects a minimum of 1.32% light at 550 nm. A silicon nitride film (η ¼ 2.01) deposit on the silicon substrate provides minimum reduced reflectance in the middle of visible spectrum having a thickness of nearly <70 nm while remaining visible wavelength region reflects 5.5% light.…”