Contact Resistance of Indium Tin Oxide and Fluorine-Doped Indium Oxide Films Grown by Ultrasonic Spray Pyrolysis to Diffusion Layers in Silicon Solar Cells

Untila, G. G., Kost, T. N., Chebotareva, A. B., & Kireeva, E. D. (2015). Contact resistance of indium tin oxide and fluorine-doped indium oxide films grown by ultrasonic spray pyrolysis to diffusion layers in silicon solar cells. Solar Energy Materials and Solar Cells, 137, 26-33.

Abstract-A simple method is described for estimating the contact resistance between a transparent conducting oxide film and a diffusion layer in a silicon solar cell. We have investigated the effect of film growth temperature on the contact resistance between n++-Si and p++-Si layers and In2O3:Sn (ITO) and In2O3:F (IFO) films grown by ultrasonic spray pyrolysis. The effect of growth temperature on the properties of the SiOx layer in IFO/SiOx/n++-Si structures has been studied by Fourier transform infrared absorption spectroscopy. The process for IFO deposition on n++-Si layers has been modified in order to reduce the IFO/SiOx/n++-Si contact resistance. The use of modified IFO has reduced the series resistance of an ITO/(p++nn++)Cz-Si/IFO bifacial solar cell for low-concentration applications by 0.13 Ω cm2, from 0.39 to 0.26 Ω cm2; extended its operating range of concentration ratios by a factor of 1.5, from 1–3.5× to 1–5.3×; and improved its efficiency in the operating range from 17.6–17.9 to 17.7–18.2%.

Keywords: Indium tin oxide; Fluorine-doped indium oxide; Ultrasonic spray pyrolysis; Crystalline silicon solar cells; FTIR

Electrical, Structural and Surface Properties of Fluorine Doped Tin Oxide Films

Bilgin, V., Akyuz, I., Ketenci, E., Kose, S., & Atay, F. (2010). Electrical, structural and surface properties of fluorine doped tin oxide films. Applied Surface Science, 256(22), 6586-6591.

Abstract-Fluorine (F) incorporated polycrystalline SnO2 films have been deposited onto glass substrates by ultrasonic spray pyrolysis technique. To possess information about the electrical properties of all films, their electrical conductivities were investigated depending on the temperature, and their activation and trap energies were analyzed. The crystalline structure, surface properties and elemental analysis of the SnO2 films were examined to determine the effect of the F element. After all investigations, it was concluded that each fluorine incorporation rate has a different and important effect on the physical properties, and SnO2:F (3 at%) films were found to be the most promising sample for energy conversion devices, especially as conducting electrode in solar cells with its improved structural and electrical properties as compared to others.

Keywords: SnO2:F films; Ultrasonic spray pyrolysis; Electrical properties; XRD; SEM; EDS

Preparation and Characterization of Ultrasonically Sprayed Zinc Oxide Thin Films Doped With Lithium

Bilgin, V. (2009). Preparation and characterization of ultrasonically sprayed zinc oxide thin films doped with lithium. Journal of electronic materials, 38(9), 1969-1978.

Abstract-Zinc oxide thin films doped with Li were deposited by ultrasonic spray pyrolysis (USP) at 350 ± 5°C on glass substrates from solutions of zinc acetate [Zn(CH3COO)2 · 2H2O] and lithium acetate [C2H3LiO2 · 2H2O], in which the Li/Li + Zn ratios were 1 at.%, 3 at.%, and 5 at.%. The effects of the doping on the structural, optical, electrical, and morphological properties of the films were examined. X-ray diffraction patterns indicated that the undoped and Li-doped ZnO films had a polycrystalline hexagonal wurtzite structure with a (002) preferred orientation. The films showed optical transmission around 60–80% in the visible region of the spectrum. The films were found to be transparent in the wavelength range of 450–900 nm, with sharp ultraviolet absorption edges in the wavelength range of 350–450 nm. The absorption edge analysis revealed that the optical band gap energies for the films were between 3.24 eV and 3.29 eV, and the electronic transition was of the direct transition type. The width of the band tail states, which is connected to the localized states in the band gap, was estimated to be 82–113 meV by Urbach tail analysis. For study of the electrical properties of the films, Hall effect measurements, electrical conductivities, conductivity activation, and trap energies were investigated. The electrical measurements of the films were obtained in the dark, in vacuum, and in the temperature range of 10–300 K. Morphological studies for the films were carried out by scanning electron microscopy.

Keywords: ZnO:Li films, ultrasonic spray pyrolysis, optical and electrical properties, x-ray diffraction (XRD),scanning electron microscopy (SEM)

The Effect of Sn Concentration on Some Physical Properties of Zinc Oxide Films Prepared by Ultrasonic Spray Pyrolysis

Bilgin, V., Kose, S., Atay, F., & Akyuz, I. (2005). The effect of Sn concentration on some physical properties of zinc oxide films prepared by ultrasonic spray pyrolysis. Journal of materials science, 40(8), 1909-1915.

Abstract-The effect of Sn concentration on zinc oxide (ZnO) film properties has been investigated by depositing films with various Sn concentrations in the solution (Sn/Sn + Zn ratio from 0 to 50 at%) at a substrate temperature of 350°C by ultrasonic spray pyrolysis (USP) technique. The deposited films were characterized for their electrical, structural, morphological and elemental properties using current-voltage and conductivity-temperature measurements, X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. Electrical investigations showed that the resistivity of ZnO films decreases for lower Sn concentration (at 10%) and then increases for higher Sn concentration (at 30–50%). Also, depending on the increasing Sn concentration, energies of donor-like traps for ZnO films decreased and activation energy of donors for ZnO films increased. The XRD patterns showed that the as-deposited films have polycrystalline structure and the crystalline nature of the films was deteriorated with increasing Sn concentration and a shift to amorphous structure was seen. The effect of Sn concentration was to increase the surface roughening and change considerably the morphologies of ZnO films. The most homogenous surface was seen in ZnO films. EDS results showed that all elements in the starting solutions were in the solid films and Zn element is more dominant than Sn on the surfaces. After all investigations, it was determined that Sn incorporation dramatically modifies the properties of ZnO films. ZnO and ZnO:Sn (10 at%) films have a low resistivity and high transparency in the visible range and may be used as window material and antireflecting coating in solar cells while the other films may be used in gas sensors where high conductivity is unnecessary.

The effect of the film thickness and doping content of SnO2: F thin films prepared by the ultrasonic spray method

Rahal, A., Benramache, S., & Benhaoua, B. (2013). The effect of the film thickness and doping content of SnO2: F thin films prepared by the ultrasonic spray method. Journal of Semiconductors, 34(9), 093003.

Abstract-This paper reports on the effects of film thickness and doping content on the optical and electrical properties of fluorine-doped tin oxide. Tin (II) chloride dehydrate, ammonium fluoride dehydrate, ethanol and HCl were used as the starting materials, dopant source, solvent and stabilizer, respectively. The doped films were deposited on a glass substrate at different concentrations varying between 0 and 5 wt% using an ultrasonic spray technique. The SnO2:F thin films were deposited at a 350 °C pending time (5, 15, 60 and 90 s). The average transmission was about 80%, and the films were thus transparent in the visible region. The optical energy gap of the doped films with 2.5 wt% F was found to increase from 3.47 to 3.89 eV with increasing film thickness, and increased after doping at 5 wt%. The decrease in the Urbach energy of the SnO2:F thin films indicated a decrease in the defects. The increase in the electrical conductivity of the films reached maximum values of 278.9 and 281.9 (Ω cm)−1 for 2.5 and 5 wt% F, respectively, indicating that the films exhibited an n-type semiconducting nature. A systematic study on the influence of film thickness and doping content on the properties of SnO2:F thin films deposited by ultrasonic spray was reported.