Mid-infrared optical properties of thin films of aluminum oxide, titanium dioxide, silicon dioxide, aluminum nitride, and silicon nitride

Abstract

The complex refractive index components, n and k, have been studied for thin films of several common dielectric materials with a low to medium refractive index as functions of wavelength and stoichiometry for mid-infrared (MIR) wavelengths within the range 1.54-14.29 μm (700-6500 cm(-1)). The materials silicon oxide, silicon nitride, aluminum oxide, aluminum nitride, and titanium oxide are prepared using room temperature reactive sputter deposition and are characterized using MIR variable angle spectroscopic ellipsometry. The investigation shows how sensitive the refractive index functions are to the O2 and N2 flow rates, and for which growth conditions the materials deposit homogeneously. It also allows conclusions to be drawn on the degree of amorphousness and roughness. To facilitate comparison of the materials deposited in this work with others, the index of refraction was also determined and provided for the near-IR and visible ranges of the spectrum. The results presented here should serve as a useful information base for designing optical coatings for the MIR part of the electromagnetic spectrum. The results are parameterized to allow them to be easily used for coating design.

Exploiting Native Al2O3 for Multispectral Aluminum Plasmonics

“…The mesh size used in the simulations was 2.5 × 2.5 × 1 nm 3 . Dielectric functions used in the simulations are from the program database (CRC data for Al and Palik data for Ag and values adapted from the literature 53 for Al 2 O 3 ). Dielectric functions of Al and Ag were fitted to polynomials with 10 −5 fit tolerance, 12 coefficients, and 12 imaginary weight using the program's fitting algorithm.…”

Photonic Gas Sensor Using a Silicon Strip Waveguide

“…A model of the strip waveguide was developed using the finite element method simulation tool COMSOL Multiphysics 5.2a. The material parameters were obtained from the literature [3,4]. A mode analysis was carried out on the cross-section of the waveguide.…”

“…From the simulation the effective index was evaluated for the two modes and is also shown in Figure 2. At λ = 4.26 µm the real part of the refractive index for Si3N4 is = 2.38 [3]. According to Equation (1), the EM field of the fundamental quasi-TE mode ( = 2.47) is therefore oscillatory in the silicon strip waveguide only and it is evanescent in the Si3N4 ( = 2.38) and gas/air region ( = 1).…”

Enhanced wavelength-selective absorber for thermal detectors based on metamaterials

“…For the top and bottom outer walls scattering boundary conditions with and without an incident wave are used, respectively. The experimental refractive index val- ues of the individual materials including the dispersion relation are taken from Kischkat et al (2012), Ordal et al (1985), and Palik (1985) and implemented in the model. The field distributions, and the time-averaged power flow in the structure is calculated.…”