Electrical and Optical Properties of Tin Oxide Films

Abstract

COMPOUNDS of the type XYZ, or XY,Z,, where X and Y are different cations and Z is a chalcogen ion, e . g . BaTiS,, (Zn,Cd)Cr,S,, and CuCr,Se,, have important electronic and magnetic properties. Many observers have synthesized such compounds by reacting the elements directly in evacuated quartz tubes. The same technique has been used with mixed chalcogenides,' and the addition of halide fluxes has greatly improved the technique.* Conversion of a complex oxide to a complex chalcogenide by the use of CS, gas at high temperature has also been demonstrated.3 With these techniques, control of crystal or particle size and distribution is very difficult, particularly because of the high temperatures involved.Electronic and magnetic properties of powders, or bulk solids derived therefrom, are extremely dependent on particle (or grain) size, shape, and size distribution. Grain size must be controlled at approximately single-domain size to optimize properties such as photomagnetism, dielectric constant, and magnetic coercivity .A method was sought, therefore, that would permit precipitation of such compounds directly at low temperatures with good stoichiometric control and that would result in very fine, uniform particles suitable for direct use or for easy sintering to bulk bodies. Nonaqueous solutions are desirable because many complex chalcogenides are hydrolyzed by water. Solutions of stearates, which are readily available, in organic solvents are suitable.Initially, in an attempt to prepare CuCr,Se,, a stream of H,Se gas (prepared by reacting water and AI,Se3) was bubbled into a dry solution of Cu and Cr stearates in xylene. The black amorphous precipitate produced could be converted into crystalline CuCr, Se, by heating it to 300°C in evacuated tubes. This result suggested that, if precipitation could be conducted at =300"C, the crystalline spinel might be produced directly. Furthermore, the handling of H,Se gas was unpleasant and awkward. Since Se will dehydrogenate sterols at -3OO"C, giving aromatic hydrocarbons and H,Se (a method used for their characterization), an internal generation was considered.Such apreparation was attempted: 23.32 g (0.05 mol on the basis of analyzed Cu) of Cu stearate and 119.02 g (0.10 mol on the basis of analyzed Cr) of Cr stearate with 35 g sitosterol* and 23.69 g Se chips (0.2 mol+ 50% excess) were stirred into 350 ml of nujol in a 3-1 reaction vessel and slowly heated to 330°C. A clear solution was obtained, since water was drivenoff at <

Solution processed SnO2:Sb transparent conductive oxide as an alternative to indium tin oxide for applications in organic light emitting diodes

“…64 Moreover, the increase in carrier concentration with increase of the Sb doping concentration is due to the fact that Sb (Sb +5 in particular) forms a shallow donor level close to the conduction band of SnO 2 . 65 The decrease however of the carrier concentration for Sb doping in excess of 2% is probably due to increased disorder that results from an increase in the activation energy of the donor. 65 The latter is consistent with the monotonic increase of the Urbach tail energy (Figure 2b) with increasing the Sb content and the steep increase in particular for Sb doping in excess of 2 %, as such an increase of the Urbach tail energy denotes increase of the density of defect states, perturbation of the parabolic density of states at the band edge, loss of stoichiometry or change of the valence state of the doping element.…”

“…65 The decrease however of the carrier concentration for Sb doping in excess of 2% is probably due to increased disorder that results from an increase in the activation energy of the donor. 65 The latter is consistent with the monotonic increase of the Urbach tail energy (Figure 2b) with increasing the Sb content and the steep increase in particular for Sb doping in excess of 2 %, as such an increase of the Urbach tail energy denotes increase of the density of defect states, perturbation of the parabolic density of states at the band edge, loss of stoichiometry or change of the valence state of the doping element. The latter in particular is further supported by the variation of the SnO 2 :Sb films (∼230 nm on fused silica) average transparency in the visible spectrum (400 nm -700 nm) that is shown is Figure 4a.…”

Electrical, structural and optical properties of SnO2 thin films prepared by spray pyrolysis

“…The crystal structure, composition, electrical conductivity and optoelectronic properties of SnO 2 films depend critically on substrate temperature, preheating rate of deposition, grain size in the film, spraying solution, design of the apparatus for spraying, quality of the substrate etc. When the extraneous impurities are added to the SnO 2 lattice [21][22][23][24], the electrical conductivity and optical transparency of SnO 2 films are increased without altering either the transparency or stability of the films.…”

Characterization of Sol-Gel Derived Antimony-doped Tin Oxide Thin Films for Transparent Conductive Oxide Application

“…Consequently, carrier concentration is increased, and resistivity is decreased, by the doping effect of Sb at a certain level of Sb-concentration, compared to those of undoped SnO 2 film. However, for high Sb-concentration of 10 mol%, a little decrease of resistivity might be due to increased disorder, which causes an increase in the activation energy of the donor [29].…”