Papers
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TL;DR: In this paper, the 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.
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.
214 citations
TL;DR: In this article, the dielectric function and the dynamic resistivity were determined from the optical spectra of a SnO 2 film for heat-reflecting purposes on borosilicate glass by hot spray technique from an aerosol of SnCl 4 in butyl acetate doped with fluorine.
Abstract: SnO 2 films for heat-reflecting purposes are prepared on borosilicate glass by the hot spray technique from an aerosol of SnCl 4 in butyl acetate doped with fluorine. Carrier densities of up to 6 × 10 20 cm −3 and mobilities in the range 10–40 cm 2 V −1 s −1 are achieved depending on the preparation methods and conditions. From the optical spectra the dielectric function and the dynamic resistivity are determined. The frequency dependence of the resistivity above the plasma edge shows that scattering by ionized impurities and neutral defects occurs.
83 citations
TL;DR: In this paper, the electrical and optical properties of thin films of highly doped oxides of In and Sn were investigated and the free electron mobility was limited mainly by ionized impurity scattering.
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.
77 citations
TL;DR: In this article, the optimal design of a heat-reflecting filter utilizing induced transmission in a thin metal film is deduced in the complex admittance plane, where the antireflection material should be highly refractive and should have a phase thickness of about λ/8.
Abstract: The optimal design of a heat-reflecting filter utilizing induced transmission in a thin metal film is deduced in the complex admittance plane. The antireflection material should be highly refractive and should have a phase thickness of about λ/8. The radiation traversing the metal film is only slightly attenuated as long as a critical thickness is not exceeded. This thickness depends on the complex refractive index of the metal and on the symmetry at the boundaries of the metal film and it can be greater than the skin depth. Above this “thickness window” the net flux ratio T/(1-R) falls off exponentially. Evaporated ZnS/Ag/ZnS filters with a silver thickness that is not too small confirm the theoretical predictions.
59 citations
12 Apr 1982
TL;DR: The performance of these filters strongly depends on the doping and preparation conditions, the upper limits of which are discussed on the basis of defect mechanisms in solids in this paper, where a few examples are described.
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.
12 citations
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TL;DR: In this paper, the authors 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.
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.
2,553 citations
TL;DR: In this paper, the authors reviewed work on In2O3:Sn films prepared by reactive e−beam evaporation of In2 O3 with up to 9 mol'% SnO2 onto heated glass.
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...
2,124 citations
TL;DR: In this paper, an extensive review of thin film materials prepared during the last 10 years is given to demonstrate the versatility of the chemical spray pyrolysis technique and various conditions to obtain thin films of metal oxide, metallic spinel oxides, binary, ternary and quaternary chalcogenides and superconducting oxides are also given.
Abstract: The chemical spray pyrolysis technique (SPT) has been, during last three decades, one of the major techniques to deposit a wide variety of materials in thin film form. The prime requisite for obtaining good quality thin film is the optimisation of preparative conditions viz. substrate temperature, spray rate, concentration of solution etc. However, in recent years an emphasis has been given to a variety of atomization techniques such as ultrasonic nebulisation, improved spray hydrolysis, corona spray pyrolysis, electrostatic spray pyrolysis and microprocessor based spray pyrolysis. This is the most critical parameter as it enables control over the size of the droplets and their distribution over the preheated substrates. The enhancement in deposition efficiency and improvement in quality of the thin films can be achieved with these atomization techniques. The detailed processes are discussed in this review. An extensive review of thin film materials prepared during the last 10 years is given to demonstrate the versatility of the chemical SPT. The various conditions to obtain thin films of metal oxide, metallic spinel oxides, binary, ternary and quaternary chalcogenides and superconducting oxides are also given. The effects of precursor, dopants, substrate temperature, post annealing treatments, solution concentration etc., on the physico-chemical properties of these films are given as well. It is observed that the properties of thin films depend very much on the preparative conditions. The properties of the thin film can be easily tailored by adjusting or optimising these conditions, which in turn are suitable for a particular application.
645 citations
TL;DR: 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 N IR-photosensitizing properties for potential applications in heat absorbers, solar cells, andNIR light-emitting diodes.
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
637 citations
TL;DR: In this article, a defect model for tin-doped In2O3:Sn is developed, which comprises two kinds of interstitial oxygen, one of which is loosely bound to tin, the other forming a strongly bound Sn2O4 complex.
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.
551 citations