V.G. Bhide

Structural properties of SnO2: F films deposited by spray pyrolysis

Abstract Transparent and conducting thin films of SnO 2 and SnO 2 : F were deposited on alkali-free Corning 7059 substrates by spray pyrolysis. The effect of various process parameters such as doping level of fluorine (in solution), substrate temperature during deposition, thickness of the film and carrier gas (air) flow rate, on the film properties was investigated by X-ray diffraction during their optimization. The optimization of the thickness was done to get the maximum value of the ratio of average visible transmission to the specific resistivity. The films deposited with the optimized process parameters have a sheet resistance of 4 ω, an average visible transmission of 86% (0.4–0.9 μm) and a thickness of 0.165 μm. The electrical conductivity of the SnO 2 : F films was ∼ 10 5 ω −1 cm −1 . The films were polycrystalline and the oxide phase observed was SnO 2 in cassiterite structure. In most of the cases the films preferentially oriented along [200]. This preferred orientation of the films was probably due to the oriented overgrowth of the films within a certain range of each process parameter. This has been explained on the basis of the standard deviation from the powder diffraction condition. It was concluded that low temperature growth was a result of adsorption-desorption phenomena whereas high temperature growth was a result of homogeneous nucleation. Since doping generally favours defect induced film growth, heavily doped films were randomly oriented. Rearrangement of grains in the films was apparent for thicker films.

Dopant induced modifications in the physical properties of sprayed ZnO : In films

Indium-doped zinc oxide (IZO) films were prepared by the spray pyrolysis technique. The effect of gradual incorporation of indium cations on the structural, electrical, and compositional properties of IZO films was studied in detail. It was observed that even a small addition of indium modifies the preferred growth of IZO film from the [002] direction to the [101] direction. Such a modification in growth pattern is a result of more nucleating centers created by indium doping. Indium dopant improves the electrical properties of the films. The carrier concentration depends mainly on the indium dopant level while the mobility is affected by the changes in crystal orientation that take place due to addition of dopants. X-ray photoelectron spectroscopy results show that indium doping does not lead to any stoichiometric changes in the IZO films and the dopant incorporation in the film is linearly proportional to that in the solution.

Development of transparent and conductive ZnO films by spray pyrolysis

Indium-doped zinc oxide (IZO) films were deposited on Corning 7059 substrates by the spray pyrolysis technique. To achieve higher electrical conductivity both the zinc acetate concentration and indium concentration in the solution were varied. The films were characterized for their structural and electrical properties. Film stability in H2 plasma was also checked for possible use in amorphous and microcrystalline silicon related fields. It was observed that the films can be sustained in a hydrogen plasma, and hence IZO films of high conductivity can be used for the development of amorphous and microcrystalline silicon solar cells.

Effect of Sn incorporation on the growth mechanism of sprayed SnO2 films

In order to probe into the growth mechanism of sprayed SnO2 films, the films were deposited with different Sn concentrations in the precursor solution. The orientational properties were determined using grazing incidence x‐ray diffraction. The preferred growth changed from [110] to [200] direction as the Sn incorporation was increased. Such a change in growth can be anticipated from structure factor calculations. The compositional analysis was done using x‐ray photoelectron spectroscopy. The Hall effect measurements indicated that the carrier concentration and mobility are sensitively dependent on the orientation and composition of the films.

Effect of dopant incorporation on structural and electrical properties of sprayed SnO2:Sb films

Antimony‐doped tin oxide films were deposited by spray pyrolysis technique. The effect of antimony doping on structural and electrical properties was investigated in detail using the x‐ray diffraction technique and room‐temperature Hall measurements. Antimony doping did not affect the preferred growth along [200] to a considerable extent. These results were analyzed on the basis of structure factor calculations. From the Hall measurements, the lowest electrical resistivity, i.e., 5.2×10−4 Ωu2009cm was observed for the films with a doping level of 2.3 at.u2009% in the solution. This value of electrical resistivity is the lowest reported so far in the case of spray deposited antimony‐doped SnO2 films. The grain boundary and ionized impurity scattering were observed to be prevalent in governing the electronic transport of lightly and heavily doped films, respectively.

Structural properties of SnO2: F films deposited by spray pyrolysis technique

Abstract Thin films of SnO 2 and SnO 2 : F were deposited by a spray pyrolysis technique. The effect of substrate temperature on the structural and electrical transport properties of these films was investigated. The standard deviation of these films from ASTM data explains the growth mechanism with other process parameters at optimum values.

Dependence of structural and electrical properties of undoped spray-deposited indium oxide thin films on deposition temperature

Abstract Thin films of undoped In 2 O 3 have been deposited at different substrate temperatures using the spray pyrolysis technique. These films show a preferred orientation which depends upon the deposition temperature of the substrate. The number of charge carriers and their mobility for the films have been measured and attempts have been made to explain these results. The results of optical transmission and energy band gap measurements are also included.

Correlation between the structural and electrical transport properties of SnO2 films

Transparent and conducting thin films of tin oxide have been deposited by spray pyrolysis on Corning 7059 substrates. The films were investigated by X-ray diffraction and Seebeck measurements to study the structural and electrical transport properties. The films were polycrystalline and the oxide phase observed was SnO2 in cassiterite structure. The films were preferentially oriented along [200]. Trap densities along [310] and [101] have been calculated for the first time. Assigning the traps mainly to the grain boundaries, the grain-boundary barrier height was calculated and compared with that obtained from the Seebeck measurements. A good agreement between these values was observed. The agreement was the best for films deposited under optimum deposition conditions.

Influence of different process parameters on physical properties of fluorine dopes indium oxide thin films

Fluorine-doped indium oxide films were prepared by the spray pyrolysis technique. The physical properties of these films were investigated with respect to various process parameters, namely variation of dopant concentration (in the solution), deposition temperature (Ts), carrier gas (air) flow rate and the thickness of the film. The best films had a Hall mobility of the order of 28 cm2V−1 s−1 and a carrier density of 2.7 × 1020 cm−3. These films were deposited at Ts=425 °C at an air flow rate of 71 min−1 for an atomic ratio of fluorine to indium of 72%. The electrical resistivity of these films was of the order of 10−4 Ω cm and the average transmission in the visible range was found to be 80–90%. The films were polycrystalline, n-type semiconductors with [400] as a preferred orientation. The preferred orientation changes from [400] to [222] depending upon the process parameters.

X-ray diffraction studies of sprayed SnO2: Sb films

Abstract Antimony-doped tin oxide films were deposited by spray pyrolysis on Corning 7059 substrates. The structural and electrical properties of the films deposited with different doping levels were studied. Relative variations in the structural properties were explained on the basis of structure factor calculations. The results show that the incorporation of antimony atoms takes place only at substitutional sites. As expected, the substitutional replacement of tin by antimony atoms increased appreciably the free carrier density of the film.