Spectroellipsometric study of the sol–gel nanocrystalline ITO multilayer films

Gärtner, M.; Losurdo, Maria; Teodorescu, V. S.; Blanchin, M. G.; Stoica, T.; Zaharescu, Maria

doi:10.1016/j.tsf.2003.11.251

Cited by 26 publications

(12 citation statements)

References 7 publications

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“…[4] Wet deposition techniques are of emerging interest due to their high cost reduction potential based on missing vacuum demand, printing possibility comprising large area fabrication potential, and the feasibility of direct patterning. Beside the several deposition methods, there exist two different principles of wet chemical processing: The sol-gel-technique, characterized by deposition of precursors with subsequent transformation into ITO [25][26][27][28][29][30] and the deposition of a dispersion containing ITO nanoparticles. [30][31][32][33][34] Sol-gel ITO films can possess adequate conductances of >350 V À1 cm À1 , [25,26,35] which can be increased to >1600 V À1 cm À1 by temperature treatment in nitrogen or forming gas.…”

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confidence: 99%

Conductance Enhancement Mechanisms of Printable Nanoparticulate Indium Tin Oxide (ITO) Layers for Application in Organic Electronic Devices

et al. 2009

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Indium tin oxide (ITO, In 2 O 3 :SnO 2 ) thin films exhibit a high conductance along with brilliant transparency in the optical range. [1][2][3] In spite of the existence of some other transparent conducting oxide materials and the high material costs, ITO is widely used as transparent electrode material in stateof-the-art optoelectronic devices such as TFT-LCD-s, [4][5] plasma TV-s, and touchscreens. It is also utilized in novel, smart optoelectronic applications including organic solar cells, [6][7] electrochromic devices, [8] and organic light emitting diodes (OLEDs) for displays [9][10][11] or for lighting. [12] Usually ITO thin films are fabricated by physical vapor deposition (PVD) methods including RF-sputtering [13,14] and magnetron sputtering [2,[15][16][17] as well as pulsed laser deposition [18,19] and several other evaporation techniques. [20][21][22][23][24] PVD derived ITO layers are characterized by high conductances of partly more than 10 000 V À1 cm À1 , [19,22] but also by high production costs. Cost drivers are the inevitable vacuum process which hinders continuous production and the requirement of substractively wet chemical patterning steps. [4] Wet deposition techniques are of emerging interest due to their high cost reduction potential based on missing vacuum demand, printing possibility comprising large area fabrication potential, and the feasibility of direct patterning. Beside the several deposition methods, there exist two different principles of wet chemical processing: The sol-gel-technique, characterized by deposition of precursors with subsequent transformation into ITO [25][26][27][28][29][30] and the deposition of a dispersion containing ITO nanoparticles. [30][31][32][33][34] Sol-gel ITO films can possess adequate conductances of >350 V À1 cm À1 , [25,26,35] which can be increased to >1600 V À1 cm À1 by temperature treatment in nitrogen or forming gas. [26,30] Due to the required low precursor to solvent ratio, only thicknesses of about 10-20 nm can be achieved for the sol-gel single layers, [26,30] which leads to high sheet resistances. To avoid this, costly repetitions of the deposition and transformation sequence are necessary.In contrast to sol-gel ITO layers, nanoparticle dispersion derived thin films enable the production of almost every thickness. They can also be produced on flexible polymer substrates, [34] but exhibit comparatively low conductances. The latter is related to a poor electrical contact between the primary particle aggregates and high inter-grain porosity. [30,32,33] Typical conductance after layer deposition is in the order of 10 À2 V À1 cm À1 and rises to several 10 0 V À1 cm À1 after annealing in air at 550 8C. [33,36] In order to overcome this conductance bottleneck, we investigated the impact of various conductance improving techniques on the electrical, optical, and morphological properties of nanoparticulate printed ITO layers. ExperimentalNanoparticulate ITO layers for electrical measurements were made by spin-coating a commercial ethanolic dispersi...

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confidence: 99%

Conductance Enhancement Mechanisms of Printable Nanoparticulate Indium Tin Oxide (ITO) Layers for Application in Organic Electronic Devices

et al. 2009

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“…Only a few template-assisted sol-gel syntheses using ITO have been reported, providing powders with quite high resistivity [6] or materials with irregular porosity resulting from the loose packing of crystallites. [7,8] Hence, subsequent functionalization of such material is significantly impeded. Mesoporous powders and macroporous films of undoped indium oxide were produced by sol-gel processes, but the resistivity of such material is usually too high for practical applications.…”

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confidence: 99%

Transparent Conducting Films of Indium Tin Oxide with 3D Mesopore Architecture

et al. 2006

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Transparent conducting oxides (TCOs) with a well-defined mesoporous framework are of considerable interest for applications in optoelectronic, electrochromic, and electroluminescent devices, solar cells, and sensors. It is the unique combination of transparency, high conductivity, well-defined 3D mesoporosity and high surface area that allows the incorporation of optoelectroactive species, facilitates electron transport to these centers, and efficiently harvests the electron-induced optical response or, vice versa, the photon-induced electron flow. These features would allow and facilitate the further development of dye-sensitized solar cells (DSSCs). However, such conducting transparent frameworks with nanometer-scale periodicity have not been accessible yet, being available solely as nonporous and macroporous layers or powders. [1][2][3] The generation of indium tin oxide (ITO) with well-ordered accessible mesoporosity and high conductivity has not been accomplished yet, partly because of the necessity of high crystallinity, which is indispensable for good electrical conductivity but inconsistent with organized 3D mesoporosity. Recently, the preparation of such mesoporous material was attempted by deposition of ITO onto porous glass substrates, providing composites with an inhomogeneous distribution of ITO. [4,5] Generally, sol-gel techniques are more advantageous for the preparation as they are applicable to various metal oxides and different types of substrates, require mild preparation conditions and, most importantly, allow the control of porosity by appropriate structure-directing agents such as self-organized surfactant micelles from block copolymers. Only a few template-assisted sol-gel syntheses using ITO have been reported, providing powders with quite high resistivity [6] or materials with irregular porosity resulting from the loose packing of crystallites. [7,8] Hence, subsequent functionalization of such material is significantly impeded. Mesoporous powders and macroporous films of undoped indium oxide were produced by sol-gel processes, but the resistivity of such material is usually too high for practical applications. [3,9] In general, the synthesis of films is aggravated by the rather poor ability of indium compounds to form stable sols and the difficulty in controlling the crystal growth of ITO. Using evaporation-induced self-assembly (EISA), various metal oxides (in particular, TiO 2[10]) have recently been obtained as crystalline thin films with ordered 3D mesoporosity. However, this technique has not been applied to certain metal oxides, particularly ITO, because of the breakdown of the mesostructure upon crystallization. The need of suitable block-copolymer templates was identified as one of the key features in the synthesis of mesoporous films with high crystallinity. [11] Owing to a new type of block copolymers with vastly improved structure-directing properties (poly(ethylene-co-butylene)-b-poly(ethylene oxides), referred to as "KLEs"), [12] we have overcome the collapse of the mesoscopi...

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“…Characteristic optical properties of thin film structures can be derived from spectroscopic SE measurement, which is known to be a high-precision optical characterization technique. [34][35][36][37][38] Variable Angle Spectroscopic Ellipsometry (VASE) allows measurements at multiple angles of incidence. A new angle will change the length of the light penetrating through the materials.…”

Section: Introductionmentioning

confidence: 99%

“…Among the several reports on the optical constants of ITO thin films evaluated by spectroscopic ellipsometry, [2][3][4]10,11,14,16,25,35 the recent work by Jung 14 is most comprehensive. Jung investigated ITO thin films prepared under various DC magnetron sputtering conditions 14 using VASE.…”

Section: Introductionmentioning

confidence: 99%

Optical analysis of room temperature magnetron sputtered ITO films by reflectometry and spectroscopic ellipsometry

et al. 2014

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Indium-tin-oxide (ITO) thin films were prepared by reactive magnetron sputtering, their optical constants and thickness were determined by spectral reflectometry (SR) in the wavelength range from 400 nm to 800 nm and spectroscopic ellipsometry (SE) in the wavelength range from 191 nm to 1690 nm. A comparative evaluation of the measured data from SR and SE has been made using the same single layer optical model based on the Cauchy dispersion relation. The introduction a surface roughness layer into the optical model considerably improved the fit quality during evaluation of SE data. Vertical inhomogeneity of the ITO thin films was assessed using a multilayer optical model describing porosity 1 gradient and the three-layer optical model suggested by Jung (Y.S. Jung, Thin Solid Films, 467, 36 (2004)) from the SE data.

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Spectroellipsometric study of the sol–gel nanocrystalline ITO multilayer films

Cited by 26 publications

References 7 publications

Conductance Enhancement Mechanisms of Printable Nanoparticulate Indium Tin Oxide (ITO) Layers for Application in Organic Electronic Devices

Conductance Enhancement Mechanisms of Printable Nanoparticulate Indium Tin Oxide (ITO) Layers for Application in Organic Electronic Devices

Transparent Conducting Films of Indium Tin Oxide with 3D Mesopore Architecture

Optical analysis of room temperature magnetron sputtered ITO films by reflectometry and spectroscopic ellipsometry

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