A Study on the Properties of MgF₂Antireflection Film for Solar Cells

Abstract

MgF 2 is a current material used for optical applications in the ultraviolet and deep ultraviolet range. Process variables for manufacturing MgF 2 thin film were established in order to clarify the optimum conditions for the growth of the thin film, dependant upon the process conditions, and then by changing a number of the vapor deposition conditions, substrate temperatures, and heat treatment conditions, the structural and optical characteristics were measured. Then, optimum process variables were thus derived. Nevertheless, modern applications still require improvement in the optical and structural quality of the deposited layers. In the present work, in order to understand the composition and microstructure of MgF 2 , single layers grown on a slide glass substrate using an Electron beam Evaporator (KV-660), were analyzed and compared. The surface substrate temperature, having an effect on the quality of the thin film, was changed from 200°C to 350°C at intervals of 50°C. The heat treatment temperature, which also has an effect on the thin film, was changed from 200°C to 400°C at intervals of 50°C. The physical properties of the thin film were investigated at various fabrication conditions, such as the substrate temperature, the heat treatment temperature, and the heat treatment time, by X-ray diffraction, and field emission-scanning electron microscopy.

Light Capture

“…However, as deposition involves expensive vacuum techniques for which large area uniformity and stability is difficult to achieve, such an approach has not been widely adopted by PV manufacturers. Experimental PV devices including CdS/CdTe 14,15 and CuInS 2 /CuGaS 2 16 solar cells have employed an evaporated thin lm of MgF 2 for antireection on the glass substrate, reducing the average top surface reectance from 5.6% to 4.3% in one case. 16 The coating material has been investigated for PV devices for operation in space but questions remain as to the stability of the lm.…”

“…Experimental PV devices including CdS/CdTe 14,15 and CuInS 2 /CuGaS 2 16 solar cells have employed an evaporated thin lm of MgF 2 for antireection on the glass substrate, reducing the average top surface reectance from 5.6% to 4.3% in one case. 16 The coating material has been investigated for PV devices for operation in space but questions remain as to the stability of the lm. 17 Low refractive index uorinated polymers have also been studied as possible SLAR coatings for glass.…”

Plasmonic active spectral filter in VIS-NIR region using metal-insulator-metal (MIM) structure on glass plate

“…After the cleaning process, the substrate was rinsed with ultrapure water and dried by an air knife consisting of a nitrogen flow. As vacuum deposition materials [16,17], granulated silver (Ag) and gold (Au) (5N, The Nilaco Co.) were prepared for the M1 and M2 layers [18][19][20][21][22][23][24][25], and granulated calcium fluoride (CaF2) [26][27][28][29][30], and magnesium fluoride (MgF2) [31][32][33][34] (Sanwa Kenma Ltd.) were used for the I layer. These materials were vacuum-evaporated by resistive heating using a tungsten (W) basket heater (Okenshoji Co., Ltd.) or a boat heater (W or Ta, The Nilaco Co.), and all three layers (M1, I, and M2) were deposited under high vacuum conditions without exposure to air.…”

Sol-Gel Derived Single Layer Zeolite-MgF2 Composite Antireflective Coatings with Improved Mechanical Properties on Polycarbonate

“…In addition, optimizing the porosity of the coating to achieve ultra-low refractive index has also been employed so as to obtain maximum transmission. MgF2 has been widely used for generating ARC on glass since it has a very low refractive index of 1.38, which can further be reduced by tailoring the porosity in the coatings [7,8].…”