The influence of thickness and index inhomogeneities on the transmission of semiconductor thin films

Bennouna, A.; Laaziz, Yassin; Idrissi, Malika

doi:10.1016/0040-6090(92)90474-p

Cited by 32 publications

(13 citation statements)

References 6 publications

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“…Thicknesses are calculated using the method described in Ref. [10]. As illustrated in Figure 3, the film thickness is a maximum in the substrate center and decreases towards the substrate edge and then increases.…”

Section: Thickness Profilementioning

confidence: 99%

“…In order to calculate the optical and physical constants from the transmission spectrum only, the latter must contain more than three interference fringes [10]. As the number of fringes is a function of film thickness, and as the film thickness was found to increase when the spinning time and the spinning speed are decreased, we have used a speed of 1800 rpm to obtain a thicker film.…”

Section: Optical Propertiesmentioning

confidence: 99%

“…The envelope of the transmission curve in the oscillating region around its extrema and the corresponding wavelengths (l max and l min ) is used to calculate the refractive index n(l). Then, film thickness and absorption coefficient are determined using a method, which takes into account the thickness inhomogeneity in the film [10]. Table I shows the results obtained assuming a thickness variation s. Dd is the standard deviation of the calculated thickness, n 1 , b, and l 0 are the constants computed from the Sellmeir law fit [18]:…”

Section: Optical Propertiesmentioning

confidence: 99%

“…Then, the structure of the films annealed at different temperatures is illustrated using the XRD measurements. The refractive index n(l), absorption coefficient a(l), optical gap energy Eg and film thickness d, are calculated from transmission spectra using an accurate optical method [10]. Electrochromism of the films is also studied using CV and chronoamperometry.…”

Section: Introductionmentioning

confidence: 99%

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Structural, Optical and Electrochromic Properties of Sol–Gel V₂O₅Thin Films

Benmoussa

Outzourhit

Jourdani

et al. 2003

Active and Passive Electronic Components

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Vanadium pentoxide thin films are prepared by the sol-gel route by dissolving V 2 O 5 powder (99.5% purity) in H 2 O 2 solution. The solution is spin-coated on glass substrates for optical (UV-VIS-NIR) and XRD analysis, and on ITOcoated glass substrates for electrochromic measurements. The samples are then annealed at 150 C for 1 hour. The resulting films have a yellow-orange color, typical of polycrystalline V 2 O 5 . XRD measurements have shown that after annealing in air at 400 C the structure of the films has a c-axis preferred orientation, the (0 0 1)-type planes lying parallel to the substrate. SEM analysis revealed a smooth surface. The films' optical and physical constants (n, a, Eg, the thickness d and the mean thickness inhomogeneity s) are calculated using a simple and accurate method based on the transmission spectrum alone. The films' electrochromism is studied using cyclic voltammetry (CV) and chronoamperometry in propylene carbonate solution containing 1 mol=l LiClO 4 . The films show reversible multichromism (yellow-green-blue) upon Li þ ion insertion=extraction. The absorbance of films colored at three different potentials is measured in the UV-VIS-PIR wavelength range, and this study shows that the changes in the optical absorption are consistent with the film color changes. Finally, the optical and electrochromic properties of the films prepared by this method are compared with those of our sputtered films already studied and with other works.

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Section: Thickness Profilementioning

confidence: 99%

Section: Optical Propertiesmentioning

confidence: 99%

Section: Optical Propertiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Structural, Optical and Electrochromic Properties of Sol–Gel V₂O₅Thin Films

Benmoussa

Outzourhit

Jourdani

et al. 2003

Active and Passive Electronic Components

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“…The normal-incidence transmittances λ of a typical 1.1-mm thick air-supported glass-slide and of air-supported selenium four-layered structures were measured at room temperature as a function of spectral wavelength λ in the range 300-1100 nm. Transmittance measurements were made using a double-beam SPECORD ® UV-Vis-NIR spectrophotometer (Analytik Jena AG Model 210) at a scan rate of 120 nm/min with a narrow spectral bandwidth (SBW) ( 4 nm) to avoid shrinking of interference-fringe pattern of as-measured λ λ spectra ( Tan, 2006;Tan et al, 2007;Tan et al, 2006;Swanepoel, 1984;Bennouna et al, 1992;Márquez et al, 1995;Ruíz-Pérez et al, 2001;Márquez et al, 1999;Pradeep & Agarwal, 2010;Richards, 1998;Richards et al, 2004) and to have good signal-to-noise ratio. Both of the λ λ spectra of the studied {air/thin a-Se-film/thick glass-slide/air}-and {air/thick glass-slide/air}-samples were recorded relative to a corrected air-baseline, where the transmittance of air was recorded with both light-beam paths were free from any sample and then normalized to 100%.…”

Section: Methodsmentioning

confidence: 99%

Determination of Optical Properties of Undoped Amorphous Selenium (a-Se) Films by Dielectric Modeling of Their Normal-Incidence Transmittance Spectra

Saleh¹,

Jafar²,

Bulos³

et al. 2014

APR

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Normal-incidence specular transmittance of undoped amorphous selenium (a-Se) films of several thicknesses ( 0.25 1 μm ) thermally evaporated on thick microscopic glass-slide substrates upheld at temperatures near 30 (below glass transition temperature of undoped Se) has been measured at room temperature in the spectral wavelength range 300 1100 nm. Above a threshold wavelength (~ 600 nm), their as-measured curves display transmittance values near that of glass substrates and exhibit well-resolved interference-fringe maxima and minima, signifying good uniformity of fabricated a-Se films. Below , the curves decline progressively to zero transmittance, preceded by a tailing-like trend of possible structural disorder origin. The spectral dependencies of optical constants and of the studied a-Se films on were retrieved from iterative curve-fitting of their -data to theoretical -formulations of an air-supported {thin film/thick substrate}-stack using the O'Leary-Johnson-Lim (OJL) interband-transition dielectric model, combined with a dielectric constant , representing the dielectric background at very high photon energies (at spectral wavelengths much smaller than measured). Regardless of the number of observed interference fringes, reliable simulation to the as-measured normal-incidence -spectra has been achieved, but were remarkably curve-fitted if we presume that a thin roughness layer ( 5 nm) of selenium was formed on top of the fabricated undoped a-Se films. The retrieved spectra display a broad peak around ≅ 0.52 μm, below which was found to vary with wavelength in accordance with a Sellmeier-like (Wemple-DiDominco) single-oscillator (normal) dispersion formula, with a static index of refraction 0 ≅ 2.42, where is the static dielectric constant of the material at zero photon energy , and an oscillator "average" bandgap energy of ≅ 3.93 eV ≅ 2 , the optical (Tauc) bandgap energy. The values of of studied undoped a-Se films deduced from Tauc-like plots were around 1.92 eV ( 0.02 eV) and the retrieved values of OJL band-tailing energy parameter (Urbach-tail parameter Γ ) was found to be in the range 40 50 meV, slightly dependent on film thickness.

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Optical absorption behaviour of vanadium pentoxide thin films

Ramana¹,

Hussain²

1997

Adv. Mater. Opt. Electron.

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Thin ®lms of vanadium pentoxide have been prepared by the electron beam evaporation technique over a wide range of substrate temperatures. Spectrophotometric investigations have been made on these ®lms in the wavelength range 350±1500 nm to determine the nature of the optically induced transition and the optical band gap. A better ®t for the direct forbidden transition than for the indirect allowed transition is observed in all the ®lms. The optical band gap is found to decrease with increasing substrate temperature and the subsequent appearance of a broadband absorption at about 1000 nm is attributed to the oxygen vacancies in the ®lms. The eect of heat treatment in vacuum and oxygen ambient on the optical properties of these ®lms is also reported.

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The influence of thickness and index inhomogeneities on the transmission of semiconductor thin films

Cited by 32 publications

References 6 publications

Structural, Optical and Electrochromic Properties of Sol–Gel V₂O₅Thin Films

Structural, Optical and Electrochromic Properties of Sol–Gel V₂O₅Thin Films

Determination of Optical Properties of Undoped Amorphous Selenium (a-Se) Films by Dielectric Modeling of Their Normal-Incidence Transmittance Spectra

Optical absorption behaviour of vanadium pentoxide thin films

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The influence of thickness and index inhomogeneities on the transmission of semiconductor thin films

Cited by 32 publications

References 6 publications

Structural, Optical and Electrochromic Properties of Sol–Gel V2O5Thin Films

Structural, Optical and Electrochromic Properties of Sol–Gel V2O5Thin Films

Determination of Optical Properties of Undoped Amorphous Selenium (a-Se) Films by Dielectric Modeling of Their Normal-Incidence Transmittance Spectra

Optical absorption behaviour of vanadium pentoxide thin films

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Structural, Optical and Electrochromic Properties of Sol–Gel V₂O₅Thin Films

Structural, Optical and Electrochromic Properties of Sol–Gel V₂O₅Thin Films