Spectroscopic Ellipsometry

Marsillac, Sylvain; Sestak, Michelle N.; Li, Jian; Collins, R. W.

doi:10.1002/9783527636280.ch6

Cited by 3 publications

(2 citation statements)

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“…Complex dielectric functions of the IGS layers in parametric form were established by least squares regression analysis of results obtained by inversion using fixed structural parameters and a fixed complex dielectric function for the underlying Mo [20]. The parametric form for IGS used here includes three terms, ε = ε 1,∞ + ε CP ( E ) + ε TL ( E ), where ε 1,∞ is an energy-independent contribution to the real part of the dielectric function, ε CP ( E ) represents a single critical point (CP) oscillator and ε TL ( E ) represents a single broad Tauc-Lorentz (TL) background oscillator.…”

Section: Methodsmentioning

confidence: 99%

“…Real time and in-situ spectroscopic ellipsometry (SE) serve as effective tools for analysis of the optical properties of individual solar cell materials and the multilayer structures of complicated thin film devices [20,21]. For example, in a study relevant to the present research, Ranjan et al have presented the complex dielectric function (ε = ε 1 − iε 2 ) spectra of CIGS obtained by SE measurements as a function of the Cu content in the film.…”

Section: Introductionmentioning

confidence: 99%

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Real Time Spectroscopic Ellipsometry Analysis of First Stage CuIn1−xGaxSe2 Growth: Indium-Gallium Selenide Co-Evaporation

et al. 2018

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Real time spectroscopic ellipsometry (RTSE) has been applied for in-situ monitoring of the first stage of copper indium-gallium diselenide (CIGS) thin film deposition by the three-stage co-evaporation process used for fabrication of high efficiency thin film photovoltaic (PV) devices. The first stage entails the growth of indium-gallium selenide (In1−xGax)2Se3 (IGS) on a substrate of Mo-coated soda lime glass maintained at a temperature of 400 °C. This is a critical stage of CIGS deposition because a large fraction of the final film thickness is deposited, and as a result precise compositional control is desired in order to achieve the optimum performance of the resulting CIGS solar cell. RTSE is sensitive to monolayer level film growth processes and can provide accurate measurements of bulk and surface roughness layer thicknesses. These in turn enable accurate measurements of the bulk layer optical response in the form of the complex dielectric function ε = ε1 − iε2, spectra. Here, RTSE has been used to obtain the (ε1, ε2) spectra at the measurement temperature of 400 °C for IGS thin films of different Ga contents (x) deduced from different ranges of accumulated bulk layer thickness during the deposition process. Applying an analytical expression in common for each of the (ε1, ε2) spectra of these IGS films, oscillator parameters have been obtained in the best fits and these parameters in turn have been fitted with polynomials in x. From the resulting database of polynomial coefficients, the (ε1, ε2) spectra can be generated for any composition of IGS from the single parameter, x. The results have served as an RTSE fingerprint for IGS composition and have provided further structural information beyond simply thicknesses, for example information related to film density and grain size. The deduced IGS structural evolution and the (ε1, ε2) spectra have been interpreted as well in relation to observations from scanning electron microscopy, X-ray diffractometry and energy-dispersive X-ray spectroscopy profiling analyses. Overall the structural, optical and compositional analysis possible by RTSE has assisted in understanding the growth and properties of three stage CIGS absorbers for solar cells and shows future promise for enhancing cell performance through monitoring and control.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Real Time Spectroscopic Ellipsometry Analysis of First Stage CuIn1−xGaxSe2 Growth: Indium-Gallium Selenide Co-Evaporation

et al. 2018

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Growth analysis of (Ag,Cu)InSe2 thin films via real time spectroscopic ellipsometry

Little

Ranjan

Collins

et al. 2012

Applied Physics Letters

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In situ and ex situ characterization methods have been applied to investigate the properties of (Ag,Cu)InSe 2 (ACIS) thin films. Data acquired from real time spectroscopic ellipsometry (RTSE) experiments were analyzed to extract the evolution of the nucleating, bulk, and surface roughness layer thicknesses. The evolution of these layer thicknesses suggests a transition from Volmer-Weber to Stranski-Krastanov type behavior when Cu is replaced by Ag. The complex dielectric functions of ACIS at both deposition and room temperature as a function of film composition were also extracted from the RTSE data, enabling parameterization of the alloy optical properties.

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Parameter determination for device simulations of thin film silicon solar cells by inverse modeling based on temperature and spectrally dependent measurements

Ostertag

Klein

Schmidt

et al. 2013

Journal of Applied Physics

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Opto-electronic device simulation of thin-film silicon solar cells requires a set of many input parameters for the electronic properties of amorphous and microcrystalline silicon. In this paper, a systematic determination of these is performed by inverse modeling and particle swarm optimization with experimental and simulated current-voltage characteristics of amorphous and microcrystalline silicon pin diodes, both in the dark and under illumination. The parameters are validated by additional experiments and simulations of the temperature-dependent dark current, of spectrally selective illumination, and of the external quantum efficiency of the amorphous and microcrystalline silicon diode, respectively. The validation of the input parameters is complemented by simulation of a tandem solar cell with the amorphous and the microcrystalline silicon input parameters. Simulation and experiment (spectrally dependent current-voltage characteristics and external quantum efficiency) of such a tandem solar cell show good agreement. Sensitivity studies on different sets of input parameters for the inverse modeling process are also presented.

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Spectroscopic Ellipsometry

Cited by 3 publications

References 52 publications

Real Time Spectroscopic Ellipsometry Analysis of First Stage CuIn1−xGaxSe2 Growth: Indium-Gallium Selenide Co-Evaporation

Real Time Spectroscopic Ellipsometry Analysis of First Stage CuIn1−xGaxSe2 Growth: Indium-Gallium Selenide Co-Evaporation

Growth analysis of (Ag,Cu)InSe2 thin films via real time spectroscopic ellipsometry

Parameter determination for device simulations of thin film silicon solar cells by inverse modeling based on temperature and spectrally dependent measurements

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