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1

New designs for graded refractive index antireflection coatings

Mahdjoub A., Zighed L.

Engineering Transactions

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2005

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Vol. 53, iss. 2

185-196

EN

The constant progress in thin layers technology, especially the graded index inhomogeneous dielectrics, allows the realization of antireflection coatings (ARC) that are less sensitive to thickness and to the incidence angle. Graded refractive index silicon oxynitrides are deposited by Electron Cyclotron Resonance Plasma-Enhanced Chemical Vapor Deposition (ECR-PECVD) controlled in-situ by monochromatic ellipsometry. While avoiding the complexity of the classical multilayer ARCs, the obtained AR coatings permit to obtain the same performances, or furthermore to improve the cells efficiency. Different suggested profiles are optimized by simulation, then they are realized and characterized by spectroscopic ellipsometry and reflectance measurement. The photogenerated current can be enhanced by 45%, and weighted reflectance (between 300 and 1100 nm) reduced to 5.6%. The passivating properties of oxinitrides recommend the use of these AR coatings on texturized surfaces. The weighted reflectance would decrease to less than 1% and short-circuit current will thus be enhanced by 52.79%.

2

Optical and microstructural properties of granded porous silicon layer

Lipiński M., Czternastek H., Sokołowski M., Panek P.

Archives of Metallurgy and Materials

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2005

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Vol. 50, iss. 2

387-393

EN

In this work we present the results of investigations of porous silicon (PS) layers for solar cells application. The PS was formed by chemical etching (stain etching) of n+-p Si substrate in a solution of HF, HNO3 and H2O. The dielectric response of a PS layer was modeled using a Bruggeman effective-medium approximation. It was shown that PS layer could be described by a model of graded layer with effective optical constants n(eff) and k(ef f) changing from these of bulk material (silicon) to these of surrounding (air). The porosity of the PS layer changed from 10% near the bulk silicon region to nearly 85% at the silicon-air interface. The effective reflectance of Cz-Si surface decreased to about 5% after PS layer formation.

PL

Przedstawiono wyniki badań własności optycznych i mikrostrukturalnych gradientowej warstwy z porowatego krzemu naniesionej metodą chamicznego trawienia. Podłożem były płytki polerowanego krzemu typu p z uformowanym złaczem n+-p. Do symulacji własności wynikających z istniejącego gradientu założono wielowarstwową strukturę porowatego krzemu stosując przybliżenie Bruggeman’a efektywnego ośrodka. Określono wartości współczynnika załamania i ekstynkcji (neff i keff) w warstwie porowatego krzemu w funkcji długosci fali światła oraz odległoćci od powierzchni krzemowego podłoża. Porowatość zmieniała się w granicach od 10% w pobliżu granicy podłoże-krzem porowaty do około 85% na granicy krzem porowaty-powietrze. Efektywny współczynnik odbicia dle krzemu z naniesiona warstwa porowatego krzemu wynosił tylko 5% w porównaniu z 25% wartoscią współczynnika odbicia od steksturyzowanej w KOH powierzchni multikrystalicznego krzemu.

3

Rare earth oxide films: their preparation and characterization

Wiktorczyk T.

Optica Applicata

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2001

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Vol. 31, nr 1

5-33

EN

Summarises the results of our investigations dealing with preparation of rare earth oxide films and examinations of their physical properties. Different deposition methods have been applied for fabrication of these films and rare-earth-oxide-based thin film coatings. The main results concerning film microstructure and optical properties in the wavelength range from the UV up to the IR are presented. Electrical and dielectric studies have been carried out in the time domain and in the frequency domain (from very low frequencies up to radio frequencies) for selected rare earth oxides. MIM sandwich-type structures have been fabricated for this aim. Trapping levels in these oxides have been investigated. The complex impedance diagnostics was applied to the analysis of the volume of the R/sub 2/O/sub 3/ film and interfacial properties (metal/insulator barriers) of M/R/sub 2/O/sub 3//M thin film structures.

4

A new method of investigation of antireflexive coatings properties at laser heating.

Przybyłowicz K., Przybyłowicz J., Depczyński W., Konieczny M.

Inżynieria Materiałowa

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2001

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R. XXII, nr 5

998-1000

EN

Efficiency of absorbing layers of various composition covered by various methods has been investigated using convergent specimens. These coatings consisted of Al2O3, iron oxide graphite SiO2 (paste) and Al2O3, B4C, Cr2O3 (plasma). The specimens were heated by CO2 laser (lambda=10,6 micrometer), power 2 kW, rate of scanning 500 mm/min. Efficiency was determined by measuring maximal thickness of melted through specimen. Additional metallographic examination in the section of maximal melting thickness has been performed, what enabled to determine the structure of melted area. It was stated that coating efficiency is the function of chemical composition and covering of the coating method.

5

Reactive antireflective coatings for laser treatment of steels.

Przybyłowicz K., Przybyłowicz J., Kusiński J.

Inżynieria Materiałowa

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1998

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R. XIX, nr 4

1047-1050

EN

In the paper experiments have been performed to find out composition of the coatings producing exothermic reaction in them under the influence of laser beam counteracting the change of steel composition and radiation of heat. The coatings are based on iron oxides mixed with carbon or metal powders of high reductive properties (silicon, magnesium, aluminium). The results have shown, that the coatings ensured high conductivity and absorptivity of heat and in many cases their neutral behaviour on heated surface has been stated.