Reflectance In IR Region Research Articles

Effect of Argon Gas Flow Rate on the Optical and Mechanical Properties of Sputtered Tungsten Thin Film Coatings

Tungsten thin film coatings were deposited on SS304 substrates by DC magnetron sputtering process. Optical and mechanical properties changes have been studied as a function of varying argon gas flow rate during magnetron sputtering process. The effect of argon flow rate on depositionrate, mechanical and optical properties of the tungsten films prepared at Different power rate was investigated by surface profilometer, nanoindenter, FESEM and UV Vis NIR spectrometer. With increasing argon gas flow rate increases deposition rate and hence higher IR reflectance in IR region and at lower argon gas flow rate the absorptance is higher. The optimized results allows us to select the deposition condition for solar absorptance and thermal emittance for solar thermal applications. The XRD analysis shows that the deposited tungsten thin film coatings were in polycrystalline in nature and surface roughness increases with increase in argon gas flow rate. Nanoindentation test result yields that hardness of DC magnetronsputtered tungsten thin film increases with argon gas flow rate from 200sccm to 500sccm.

Role of complexing agents on chemicalbath deposited PbS thin film characterization

In the present work, lead sulphide thin films have been grown on soda lime glass substrates by chemical bath deposition technique using three different complexing agents, namely triethanolamine, diethanolamine and hexamine. Aqueous solutions of lead acetate complexed with the above mentioned ligands were used as cationic precursor and thioacetamide as anionic precursor. The structural, morphological, optical and electrical properties of the as-prepared samples were investigated and compared by means of X-ray diffraction (XRD), Scanning electron microscopy (SEM), optical and electrical studies. The films were well crystallized and highly adherent to the substrate with face centered cubic structure. The average crystallite size was found to be in the range 15-20nm. The SEM micrographs showed variations in morphology. Optical studies revealed that the direct band gap energy was in the range of 1.65-2.27eV. The transmittance and reflectance in IR region was respectively in the range of 14%-47% and 25-45%. Optical constants of all films were determined by absorbance and reflection measurements. The room temperature conductivity of the PbS thin films were in the range 9.67×10−9 (Ω-Cm)−1-3.29×10−6(Ω-Cm)−1. The optical band gap energy has inverse relation with grain size and electrical conductivity is closely related to structural parameters like grain size, crystallinity and microstrain. PbS thin film using hexamine as complexing agent was proved to be the best in structural, optical and electrical properties. In this attempt we establish that the use of different complexing agents have immense effect on structural, morphological, optoelectronic and transport properties of PbS thin films.

Control of thermal barrier performance by optimized nanoparticle size and experimental evaluation using a solar simulator

An experimental investigation to evaluate the radiative properties of a selectively transparent thin coating on a substrate of a different material has been performed in order to evaluate its thermal behavior for applications where a low temperature at the surface exposed to the sun is desired. Copper (II) oxide (CuO) micro-particles have been used to create a pigmented coating on a paper substrate. The particle volume fraction and size have been optimized by the theoretical methodology. The spectral reflectance was measured using spectroscopy in the visible (VIS) and near-infrared (NIR) regions. The spectral emissivity was evaluated from the reflectance in IR region. The temperatures of the designed coatings and typical black paints are measured in a solar simulator. The temperature measurement was simulated by numerical analysis. The temperature of CuO coating on standard white paper was 10°C lower than the ones of typical black paint while keeping the desired dark tone.

Properties of Al Doped ZnO Thin films by DC Reaction Magnetron Sputtering

The high quality ZAO thin films were successfully produced by DC reaction magnetron sputtering technology. The XRD，electrical and optical properties of films are particular investigated. The results show that ZAO films are polycrystalline hexagonal wurtzite structure，and Al2O3 crystal phase are not found. At the same time，the high quality ZAO films with the minimum resistivity of 4.5x10-4Ω•㎝, the transmittance in visible region above 80% and the reflectivity in IR region above 70% are gained.

Analysis of ZAO Thin Films by DC Reaction Magnetron Sputtereing

The high quality ZAO thin films were produced by DC reaction magnetron sputtering technology. The XRD, electrical and optical properties of ZAO thin films were particularly investigated. The results show that ZAO films are polycrystalline hexagonal wurtzite structure，and Al2O3 crystal phase are not found. At the same time，the high quality ZAO films with the minimum resistivity of 4.5x×10-4Ω·㎝, the transmittance in visible region above 80% and the reflectivity in IR region above 70% are gained.

Study on XRDK Optical and Electrical performance of Transparent Conducting ZnO:Al(ZAO) Thin Films

The ZAO (ZnO: Al) thin films were prepared by DC reactive magnetron sputtering technique. The XRD electrical and optical properties of films are particular investigated. The results show that ZAO films are polycrystalline hexagonal wurtzite structure, and we are not find Al2O3 crystal phase. At the same time, we gained the high quality ZAO films with the minimum resistivuty of 4.5×10-4 Ω · cm, the transmittance in visible region above 80% and the reflectivity in IR region above 70%.

The effect of the ion beam energy on the properties of indium tin oxide thin films prepared by ion beam assisted deposition

Indium tin oxide (ITO) thin films have been deposited onto polycarbonate substrates by ion beam assisted deposition technique at room temperature. The structural, optical and electrical properties of the films have been characterized by X-ray diffraction, atomic force microscopy, optical transmittance, ellipsometric and Hall effect measurements. The effect of the ion beam energy on the properties of the films has been studied. The optical parameters have been obtained by fitting the ellipsometric spectra. It has been found that high quality ITO film (low electrical resistivity and high optical transmittance) can be obtained at low ion beam energy. In addition, the ITO film prepared at low ion beam energy gives a high reflectance in IR region that is useful for some electromagnetic wave shielding applications.

Bi2-xInxSe3 crystals; optical properties and transport coefficients

Single crystals of Bi2-xInxSe3 (x = 0.0-0.66) were prepared from the elements of 5N purity using the modified Bridgman method. On the samples with a various content of incorporated In-atoms the reflectivity in IR-region and the transport coefficients (electrical conductivity σ⊥, Hall coefficient RH (B ∥ c), Seebeck coefficient S⊥) were measured. The results showed that the In-atoms incorporation to the crystal lattice of Bi2Se3 in the region of small concentrations of In-atoms increases the free carriers concentration, in the region of higher concentrations of In-atoms the free carriers concentration is suppressed. On the ground of measured changes in the values of transport coefficients and optical parameters (determined from the interpretation of infrared reflectivity) a model of point defects in the Bi2-x Inx Se3 crystal lattice has been suggested. This model takes into account the existence of antisite defects Bi'Se in the Bi2Se3 crystal lattice the concentration of which is suppressed by incorporated In-atoms. The built-in In-atoms form uncharged defects InxBi which are positively polarized.

Preparation and some physical properties of Bi2Se3−xSx mixed crystals

Abstract Single crystals of Bi 2 Se 3− x S x (x = 0−0.45) were prepared by the modified Bridgman method. The homogeneity of the crystals was proved by X-ray fluorescence analysis and measurement of reflectivity spectra. Measurement of the crystal lattice parameters by the powder X-ray diffraction method showed that with increasing sulfur content the value of the lattice parameter c increases and a decreases. From the measurement of reflectivity in IR region, the electrical conductivity and the Hall coefficient, some basic physical parameters of Bi 2 Se 3− x S x crystals were obtained which characterize the crystals as semiconductors.