Oxygen plasma effects on optical properties of ZnSe films

Abstract

Zinc selenide is an infrared transparent semiconductor material being considered for use in space as an infrared optical coating. In this work, zinc selenide thin films of different thicknesses were exposed to an electron cyclotron resonance generated oxygen plasma, often used to ''simulate'' the low earth orbital environment. The maximum fluence used in our experiments was equivalent to ϳ16 years in the low earth orbital environment. ZnSe thin film optical constants ͑both before and after oxygen plasma exposure͒ were determined using variable angle spectroscopic ellipsometry from the vacuum ultraviolet at 146 nm through the middle infrared to 40 m. A parametric dispersion model ͑Herzinger-Johs͒ was successfully used to fit the optical data over the entire range from ultraviolet to infrared. Comparing the pre-and post-oxygen plasma exposure data, few changes were observed in the middle infrared region, while drastic changes were seen in the vacuum ultraviolet through visible to near infrared ͑0.73-8.5 eV͒. This suggests that chemical changes upon plasma exposure, including oxidation, are found mainly in a thin layer near the surface. As the proposed application is for infrared coatings, and few infrared changes were seen under conditions roughly equivalent to 16 years in low earth orbit, ZnSe may indeed be useful for space infrared applications. Performance simulations of ZnSe coated infrared-operating electrochromic thermal-control surfaces confirm this conclusion.

Structure and optical properties of polycrystalline ZnSe thin films: validity of Swanepol’s approach for calculating the optical parameters

“…The estimated refractive index values which are corresponding to the film thickness (224-633 nm) range from 2.14 to 2.48. ZnSe thin films at lower thickness which have high refractive index values make these films suitable for solar cells and antireflective applications [50]. The values of refractive index (n) in whole wavelengths which calculated using Cauchy's dispersion relationship as:…”

Comparison of ion post treatment and laser conditioning of thin films

“…The limited research results indicate that ion posttreatment is an effective technique for modifying film properties, and many properties have been improved by this technique. Yan et al studied the effects on the optical properties of ZnSe films, and obtained satisfactory results 11 . Unfortunately, to our knowledge, almost no work has been done on the effects of ion posttreatment on the LIDT of optical coatings.…”

Influence of Annealing Temperature Modulation on the Structural and Optical Properties of ZnSe Thin Films

“…[11][12][13] In terms of basic optical properties, ZnSe can used in solar cells, protective and antireflection coating, blue laser diodes, light-emitting diodes, photodetector, and sensors. [14][15][16][17][18][19][20][21][22] With the rapid development of lasers, traditional linear optical devices have not been able to meet some specific requirements of high power laser and military fields. Therefore, nonlinear optical absorption (NOA) behaviors of chalcogenide thin films gradually attracted much attention of the researchers.…”