E. Kauer

Bio: E. Kauer is an academic researcher from Philips. The author has contributed to research in topics: Thin film & Doping. The author has an hindex of 4, co-authored 4 publications receiving 301 citations.

Transparent heat-reflecting coatings based on highly doped semiconductors☆

Abstract: Thin films of doped SnO2 and In2O3 are used as transparent heat reflectors. Free electron densities of up to 1021 cm−3 and mobilities in the range 10–70 cm2 V−1s−1 can be obtained by means of an appropriate doping and/or oxygen deficit. Tin, acting as an electron donor, is soluble in In2O3 up to 6 at.%. After an oxidizing heat treatment the electrons of the donors are extensively trapped and the mobility of the remaining electrons is decreased. The cut-off wavelength between the transparent and reflecting spectral regions can be adjusted by the plasma wavelength of the free electrons, i.e. by the electron density. The filter losses due to visiblw absorption and incomplete IR reflection are discussed and these demonstrate the importance of a high free electron mobility. The influence of the surface resistance and the angle of observation on the thermal emissivity was measured. Some examples of the application and specific optimization of In2O3 thin films, which are produced by spray pyrolysis, are presented.

Transparent heat-reflecting coatings for solar applications based on highly doped tin oxide and indium oxide

Abstract: The electrical and optical properties of thin films of the highly doped oxides of In and Sn are investigated. Maximum free electron densities of 15 × 10 20 cm −3 in In 2 O 3 and 7 × 10 20 cm −3 in SnO 2 are obtained in films prepared by the hot spray technique by appropriate doping. Free electron density and mobility are strongly influenced by additional oxygen. The free electron mobility is limited mainly by ionized impurity scattering. Optimized filters are designed for solar collector and window applications, taking into account a modified Drude behaviour.

Transparent Heat Reflecting Coatings (THRC) Based On Highly Doped Tin Oxide And Indium Oxide

Abstract: A number of highly doped oxides - in particular Sn02 and In203 - have been reported to show high infrared reflectivity while being transparent to visible radiation. Their optical behaviour is based on metal-like properties i.e. high concentration and mobility of the conduction electrons and a semiconductor bandgap of about 3 eV or higher. Thin films of these oxides can be adapted for many applications and a few examples will be described. The performance of these filters strongly depends on the doping and preparation conditions. Coatings prepared by spray pyrolysis show excellent electrical and optical properties, the upper limits of which are being discussed on the basis of defect mechanisms in solids.© (1982) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Transparente wärmereflektierende Schichten auf der Basis hochdotierter Halbleiter

Abstract: Auf der Basis hochdotierter Halbleiter, wie beispielsweise Sb-dotiertem SnO2 und Sn-dotiertem In2O3, lassen sich lichtdurchlassige warmereflektierende Schichten herstellen. Diese eignen sich in einer Reihe von Anwendungsfallen ausgezeichnet zur Verminderung der Warmestrahlungsverluste und damit zur Verbesserung der Energiebilanz. Als typische Anwendung solcher Filter in energiesparenden Systemen werden Natriumdampflampen mit erhohter Warmeisolation, Sonnenkollektoren mit hohem Wirkungsgrad und Doppelfenster mit kleinem Warmedurchgang beschrieben.

Transparent conductors—A status review

Abstract: Non-stoichiometric and doped films of oxides of tin, indium, cadmium, zinc and their various alloys, deposited by numerous techniques, exhibit high transmittance in the visible spectral region, high reflectance in the IR region and nearly metallic conductivity. The electrical as well as the optical properties of these unusual materials can be tailored by controlling the deposition parameters. These transparent conductors have found major applications in a vast number of active and passive electronic and opto-electronic devices ranging from aircraft window heaters to charge-coupled imaging devices. In this status review we present a comprehensive and up-to-date description of the deposition techniques, electro-optical properties, solid state physics of the electron transport and optical effects and some applications of these transparent conductors.

Evaporated Sn‐doped In2O3 films: Basic optical properties and applications to energy‐efficient windows

Abstract: We review work on In2O3:Sn films prepared by reactive e‐beam evaporation of In2O3 with up to 9 mol % SnO2 onto heated glass. These films have excellent spectrally selective properties when the deposition rate is ∼0.2 nm/s, the substrate temperature is ≳150 °C, and the oxygen pressure is ∼5×10−4 Torr. Optimized coatings have crystallite dimensions ≳50 nm and a C‐type rare‐earth oxide structure. We cover electromagnetic properties as recorded by spectrophotometry in the 0.2–50‐μm range, by X‐band microwave reflectance, and by dc electrical measurements. Hall‐effect data are included. An increase of the Sn content is shown to have several important effects: the semiconductor band gap is shifted towards the ultraviolet, the luminous transmittance remains high, the infrared reflectance increases to a high value beyond a certain wavelength which shifts towards the visible, phonon‐induced infrared absorption bands vanish, the microwave reflectance goes up, and the dc resisitivity drops to ∼2×10−4 Ω cm. The corre...

Near‐Infrared Organic Compounds and Emerging Applications

Abstract: This Focus Review describes the emerging class of near-infrared (NIR) organic compounds containing the conjugated polyene, polymethine, and donor-acceptor chromophores and exploration of their NIR-absorbing, NIR-fluorescence, and NIR-photosensitizing properties for potential applications in heat absorbers, solar cells, and NIR light-emitting diodes Examples of NIR organic compounds are reviewed with emphasis on the molecular design, NIR absorption, and fluorescence and particular emerging applications The donor-acceptor type of NIR chromophores are particularly introduced owing to some unique features, including the designer-made energy gaps, facile synthesis, good processability, and controllable morphology and properties in the solid state Future directions in research and development of NIR organic materials and applications are then offered from a personal perspective

Electrical properties and defect model of tin-doped indium oxide layers

Abstract: Tin-doped In2O3 layers were prepared by the spray technique with doping concentrationsc Sn between 1 and 20 at. % and annealed at 500 °C in gas atmospheres of varying oxygen partial pressures. The room-temperature electrical properties were measured. Maximum carrier concentrationsN=1.5×1021cm−3 and minimum resistivities ϱ=1.3×10−4 Ω cm are obtained if the layers are doped withc Sn≈9 at. % and annealed in an atmosphere of oxygen partial pressurep O2 ⋦10−20 bar. At fixed doping concentration, the carrier mobility increases with decreasing oxygen pressure. The maximum obtainable mobility can be described in terms of electron scattering by ionized impurities. From an analysis of the carrier concentration and additional precision measurements of the lattice constants and film thicknesses, a defect model for In2O3:Sn is developed. This comprises two kinds of interstitial oxygen, one of which is loosely bound to tin, the other forming a strongly bound Sn2O4 complex. At low doping concentrationc Sn≲4 at. % the carrier concentration is governed by the loosely bound tin-oxygen defects which decompose if the oxygen partial pressure is low. The carrier concentration follows from a relationN=K 1 ·p O2 −1/8 ·(3 ×1010 × cSn −N)1/4 with an equilibrium constantK 1=1.4×1015 cm−9/4bar1/8, determined from our measurements.

Semiconducting transparent thin films: their properties and applications

Abstract: The present state of the art of transparent, electrically conducting films, with special reference to In2O3, SnO2 and Cd2SnO4, has been reviewed. Various production techniques currently in use, and typical parameters used in the processes have been discussed in detail. Electrical and optical properties of these films have been reported as a function of various parameters, e.g. substrate temperature, doping, oxygen pressure, etc. Finally, the applications of these films in research and industry have been discussed in detail.