DETERMINATION OF THE OPTICAL CONSTANTS OF InxSey THIN FILMS DEPOSITED BY EVAPORATION AND COEVAPORATION

2002 ◽  
Vol 09 (05n06) ◽  
pp. 1687-1691 ◽  
Author(s):  
J. SANDINO ◽  
G. GORDILLO

In x Se y thin films, grown on soda lime glass substrates in the In 6 Se 7 phase by evaporation of the In 2 Se 3 compound and in the In 2 Se 3 phase by coevaporation of In and Se, were optically characterized through spectral transmittance measurements. A special procedure was developed to determine the thickness d and the optical constants (refractive index n, absorption coefficient α, and optical gap Eg). This includes experimental measurements of the spectral transmittance and the use of a model taking into account interference effects induced by internal reflections presented in the interfaces substrate/film and film/air and the fitting of the n vs. λ curve to the Cauchy equation (n = A + B/λ2). The optical constants of the In x Se y thin films were corrected comparing the experimental transmittance spectrum with the theoretical one. The results revealed that the optical constants of the In x Se y films were significantly affected by the deposition method.

2005 ◽  
Vol 865 ◽  
Author(s):  
P. D. Paulson ◽  
S. H. Stephens ◽  
W. N. Shafarman

AbstractVariable angle spectroscopic ellipsometry has been used to characterize Cu(InGa)Se2 thin films as a function of relative Ga content and to study the effects of Cu off-stoichiometry. Uniform Cu(InGa)Se2 films were deposited on Mo-coated soda lime glass substrates by elemental evaporation with a wide range of relative Cu and Ga concentrations. Optical constants of Cu(InGa)Se2 were determined over the energy range of 0.75–C4.6 eV for films with 0 ≤ Ga/(In+Ga) ≤ 1 and used to determine electronic transition energies. Further, the changes in the optical constants and electronic transitions as a function of Cu off-stoichiometry were determined in Cu-In-Ga-Se films with Cu atomic concentration varying from 10 to 25 % and Ga/(In+Ga) = 0.3. Films with Cu in the range 16–24 % are expected to contain 2 phases so an effective medium approximation is used to model the data. This enables the relative volume fractions of the two phases, and hence composition, to be determined. Two distinctive features are observed in the optical spectra as the Cu concentration decreases. First, the fundamental bandgaps are shifted to higher energies. Second, the critical point features at higher energies become broader suggesting degradation of the crystalline quality of the material.


2013 ◽  
Vol 716 ◽  
pp. 325-327
Author(s):  
Xiao Yan Dai ◽  
Cheng Wu Shi ◽  
Yan Ru Zhang ◽  
Min Yao

In this paper, CdTe thin films were deposited on soda-lime glass substrates using CdTe powder as a source by close-spaced sublimation at higher source temperature of 700°C. The influence of the deposition time and the source-substrate distance on the chemical composition, crystal phase, surface morphology and optical band gap of CdTe thin films was systemically investigated by energy dispersive X-ray spectroscopy, X-ray diffraction, scanning electron microscope and the ultraviolet-visible-near infrared absorption spectra, respectively. At the deposition time of 60 min and the source-substrate distance of 5 mm, the CdTe thin films had pyramid appearance with the grain size of 15 μm.


2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Weimin Li ◽  
Xia Yan ◽  
Armin G. Aberle ◽  
Selvaraj Venkataraj

Molybdenum (Mo) thin films are widely used as rear electrodes in copper indium gallium diselenide (CIGS) solar cells. The challenge in Mo deposition by magnetron sputtering lies in simultaneously achieving good adhesion to the substrates while retaining the electrical and optical properties. Bilayer Mo films, comprising five different thickness ratios of a high pressure (HP) deposited bottom layer and a low pressure (LP) deposited top layer, were deposited on 40 cm × 30 cm soda-lime glass substrates by DC magnetron sputtering. We focus on understanding the effects of the individual layer properties on the resulting bilayer Mo films, such as microstructure, surface morphology, and surface oxidation. We show that the thickness of the bottom HP Mo layer plays a major role in determining the micromechanical and physical properties of the bilayer Mo stack. Our studies reveal that a thicker HP Mo bottom layer not only improves the adhesion of the bilayer Mo, but also helps to improve the film crystallinity along the preferred [110] direction. However, the surface roughness and the porosity of the bilayer Mo films are found to increase with increasing bottom layer thickness, which leads to lower optical reflectance and a higher probability for oxidation at the Mo surface.


2017 ◽  
Vol 2 (1) ◽  
pp. 54-59 ◽  
Author(s):  
Shih-Fan Chen ◽  
Shea-Jue Wang ◽  
Win-Der Lee ◽  
Ming-Hong Chen ◽  
Chao-Nan Wei ◽  
...  

The back contact electrode with molybdenum (Mo) thin film is crucial to the performance of Cu(In, Ga)Se2 solar cells. In this research, Mo thin films were fabricated by direct current sputtering to attain low-resistivity molybdenum films on soda-lime glass substrates with good adhesion. The films were sputtered onto substrates in 500 nm thickness and nominally held at room temperature with deposition conditions of power and working pressure. Low resistivity (17-25 μΩ∙cm) of bi-layer molybdenum thin films were achieved with combination of top layer films deposited at 300 W with different working pressure, and bottom fixing layer film deposited at 300 W with 2.5 mTorr which adhered well on glass. Films were characterized the electrical properties, structure, residual stress, morphology by using the Hall-effect Measurement, X-ray Diffraction, and Field-Emission Scanning Electron Microscopy, respectively, to optimize the deposition conditions.


1996 ◽  
Vol 436 ◽  
Author(s):  
C. R. Ottermann ◽  
K. Bange ◽  
A. Braband ◽  
H. Haefke ◽  
W. Gutmannsbauer

AbstractAdhesion failures of Ti2 and Ta2O5 thin films deposited by reactive evaporation (RE), reactive ion plating (IP) and plasma impulse chemical vapour deposition (PICVD) on fused silica, AF 45, TEMPAX and soda-lime glass substrates are investigated by means of a micro-scratch tester. The oxide films possess thickness between 60 and 500 nm and show different mass densities depending on the deposition conditions. Scratch testing exhibits well pronounced detachment for thicker films on hard substrates. The clearance of the scratch signal is reduced with decreasing layer thickness or for softer substrate materials. The test results are also influenced by the various substrates and different chemical and mechanical properties of the films due to the alternate deposition techniques.


2014 ◽  
Vol 1603 ◽  
Author(s):  
Yong Yan ◽  
Shasha Li ◽  
Zhou Yu ◽  
Yong Zhang ◽  
Yong Zhao

ABSTRACTCu2ZnSnSe4 films were deposited on soda lime glass substrates at room temperature by one-step radio frequency magnetron-sputtering process. The effect of sputtering power on the properties of one-step deposited Cu2ZnSnSe4 thin films has been investigated. The deposited films might be suitable for the absorber layers in the solar cells. The chemical composition and the preferred orientation of the films can be optimized by the sputtering power.


2001 ◽  
Vol 697 ◽  
Author(s):  
Hisayuki Suematsu ◽  
Tsuyoshi Saikusa ◽  
Tsuneo Suzuki ◽  
Weihua Jiang ◽  
Kiyoshi Yatsui

AbstractThin films of titanium iron (TiFe) were prepared by a pulsed ion-beam evaporation (IBE) method. A pulsed ion beam of proton accelerated at 1 MV (peak) with a pulse width of 50 ns and a current of 70 kA was focused on TiFe alloy targets. Soda lime glass substrates were placed in front of the targets. Phases in the thin films were identified by X-ray diffraction (XRD). XRD results revealed that the thin films deposited on the glass substrates consist of a TiFe phase. Crystallized Ti-Fe thin films without oxides were successfully obtained. Surface roughness of the thin film was 0.16 m m.


2021 ◽  
Vol 13 (1) ◽  
pp. 9-20
Author(s):  
N. H. Sheeba ◽  
A. Namitha ◽  
K. M. Ramsiya ◽  
T. M. Ashitha ◽  
R. Suhail

Polycrystalline nanostructured PbS thin films are deposited onto soda-lime glass substrates by the method of chemical bath deposition (CBD) at different duration of deposition time. The structure and surface morphology of the films are characterized by X-ray diffraction (XRD) and field effect scanning electron microscopy (FE-SEM). XRD pattern exhibits polycrystalline structure with preferential orientation along (200) direction, parameters such as crystallite size, lattice constant, lattice-strain and dislocation density are calculated. The FE-SEM images show appearance of flower like structure on formation of PbS films which is indicative of suitability in gas sensing applications. Studies on optical properties carried out by UV-Vis spectroscopy measurements show bandgap in the range 1.65eV – 1.41eV. The photoluminescence spectra of the films exhibit two peaks centered at around 613 nm and 738 nm after excitation at 450 nm. Electrical studies from Hall measurements indicate the carrier concentration and mobility of the PbS samples corroborate the variations in the conductivity.


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