Optical dispersion relations for amorphous semiconductors and amorphous dielectrics

Forouhi, A. Rahim; Bloomer, Iris

doi:10.1103/physrevb.34.7018

Cited by 733 publications

(321 citation statements)

References 30 publications

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“…One, based on a calculation of Forouhi and Bloomer (F&B) [20], has received some attention, but is flawed by the assumption that k(E)>O for E<E,, where E, is the band gap of the amorphous semiconductor; the F&B approximation also is incorrect in the limits as E+O (for metals), and as E+-, and the Kramers-Kronig determination of the real part is incorrect. A more realistic model [21] is given by…”

Section: (15)mentioning

confidence: 99%

The calculation of thin film parameters from spectroscopic ellipsometry data

Jellison

1996

Thin Solid Films

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Section: (15)mentioning

confidence: 99%

The calculation of thin film parameters from spectroscopic ellipsometry data

Jellison

1996

Thin Solid Films

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“…1 shows the measured variation of the refractive index (real and imaginary part) of a 1 µm thick GaAsPN layer at a 70° angle of incidence and the corresponding absorption, which vanishes below 1.7 eV. The experimental data have been fitted using a dispersion models (Forouhi et al 1986;Adachi 1989) for the GaAsPN layer and its native oxide respectively.…”

Section: Gaaspn Absorbing Layermentioning

confidence: 99%

Design of a lattice-matched III–V–N/Si photovoltaic tandem cell monolithically integrated on silicon substrate

et al. 2014

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Abstract. In this paper, we present a comprehensive study of high efficiencies tandem solar cells monolithically grown on a silicon substrate using GaAsPN absorber layer. InGaAs(N) quantum dots and GaAsPN quantum wells have been grown recently on GaP/Si susbstrate for applications related to light emission. For photovoltaic applications, we consider the GaAsPN diluted nitride alloy as the top junction material due to both its perfect lattice matching with Si and ideal bandgap energy for current generation in association with the Si bottom cell. Numerical simulation of the top cell is performed. The effect of layer thicknesses and doping on the cell efficiency are evidenced. In these structures a tunnel junction (TJ) is needed to interconnect both the top and bottom sub-cells. We compare the simulated performances of different TJ structures and show that the GaP(n+)/Si(p+) TJ is promising to improve performances of the current-voltage characteristic.

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“…This paper focuses on the determination of a reliable physical model to describe the optical properties of these materials. Utilizing Forouhi and Bloomer (FB) dispersion model [15], we performed multi-layer analysis to estimate the dielectric function of these n-C:S thin films. According to this five parameter model (A, B, C, n(-), and Eg) [15], the optical absorption in the visible range is dominated by a single type of electronic transition involving states within -5eV of the Fernii level and hence should involve mostly t-int' excitations.…”

Section: Introductionmentioning

confidence: 99%

“…Utilizing Forouhi and Bloomer (FB) dispersion model [15], we performed multi-layer analysis to estimate the dielectric function of these n-C:S thin films. According to this five parameter model (A, B, C, n(-), and Eg) [15], the optical absorption in the visible range is dominated by a single type of electronic transition involving states within -5eV of the Fernii level and hence should involve mostly t-int' excitations. In order to investigate the optical absorption processes in the disordered carbon material in thin film form studied hereby, fits to the pseudodielectric SE data were performed using Levenberg-Marquardt [16] algorithm while varying all the parameters to fit simultaneously both n and k spectra.…”

Section: Introductionmentioning

confidence: 99%

Optical Characterization and Modeling of Sulfur Incorporated Nanocrystalline Carbon Thin Films Deposited By Hot Filament CVD

Gupta

Weiner²,

Morell

2001

MRS Proc.

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Sulfur incorporated nanocrystalline carbon (n-C:S) thin films grown on molybdenum substrates by hot-filament chemical vapor deposition (HFCVD) using gas mixtures of methane, hydrogen and a range of hydrogen sulfide (H 2 S) concentrations are optically examined using Raman spectroscopy (RS) and ex situ spectroscopic phase modulated ellipsometry (SPME) from near IR to near UV (1.5-5.0 eV) obtaining their vibrational frequencies and pseudodielectric function, respectively. The ellipsometry data (, ) were modeled using Bruggeman effective-medium theory (BEMT) and five parameters Forouhi and Bloomer (FB) dispersion Model. A simplified two-layer model consisting of a top layer comprising an aggregate mixture of sp 3 C+sp 2 C+void and a bulk layer (L 2 ), defined as a dense amorphized FB-modeled material was found to simulate the data reasonably well. Through these simulations, it was possible to estimate the dielectric function of our n-C: S material, along with the optical bandgap (Eg), film thickness (d), and roughness layer (a) as a function of [H 2 S]. The physical interpretation(s) of the modeling parameters obtained were discussed. The Raman and ellipsometry results indicate that the average size of nanocrystallites in the sulfur-incorporated carbon thin films becomes smaller with increasing H 2 S concentration, consistent with AFM measurements. The bandgap was found to decrease systematically with increasing H 2 S concentration, indicating the 2 enhancement of midgap states and sp C network, in agreement with RS results. These results are compared to those obtained for the films grown without sulfur (n-C), in order to study the influence of sulfur addition to the CVD process. This analysis led to a correlation between the film microstructure and its electronic properties. INTRODUCTIONA great deal of attention has been given to diamond and diamond-like carbon (DLC) thin films since their advent owing to a wide range of desired and unique mechanical, optical and electronic properties (such as: high mechanical hardness, chemical inertness, negative electron affinity, and very high electron and hole mobilities) [1,2]. This combination of superlative properties paves their way to several potential and technological applications: optical coatings, wide-band IR transmissive windows, and flat panel displays (FPDs) to name a few [3]. It is also well known that the optical and electronic properties of these carbon materials are controlled by the ratio of sp

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Optical dispersion relations for amorphous semiconductors and amorphous dielectrics

Cited by 733 publications

References 30 publications

The calculation of thin film parameters from spectroscopic ellipsometry data

The calculation of thin film parameters from spectroscopic ellipsometry data

Design of a lattice-matched III–V–N/Si photovoltaic tandem cell monolithically integrated on silicon substrate

Optical Characterization and Modeling of Sulfur Incorporated Nanocrystalline Carbon Thin Films Deposited By Hot Filament CVD

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