Papers by Keyword: Transparent Conductor

Abstract: The synthesis and characterization of spin-coated Al-doped ZnO (AZO) thin films with varying Al concentrations (0%, 5%, 10%, 15% and 20%) onto glass substrates have been demonstrated in this paper. The structural, electrical and optical properties of the spin-coated thin films have been investigated by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray (EDX) analysis, Van Der Pauw method and UV-visible spectroscopy. The EDX study shows well-defined peaks which confirm the presence of only Zn, O and Al and no other impurities in the films. The increase of Al and decrease of Zn weight percentages with increasing doping level confirms the effective substitution of Zn by Al. SEM of the surfaces of the films shows that undoped ZnO films contain particle agglomeration which is reduced with Al doping and the surfaces of the films gradually became more uniform. The thickness of the AZO films varied from 86 to 699 nm with increasing Al doping concentration. The electrical conductivity of the films increased up to ~ 7 × 10^-2 (Ω.cm)^-1 due to doping with 5% Al concentration. The optical transmittance highly increased above 95% in the visible range with the introduction of Al dopant and it kept rising with the increase of Al concentration. The optical energy band gap of undoped ZnO increased from 3.275eV to 3.342 eV with 5% Al doping.

Abstract: Thin layers of tin oxide have numerous applications in various branches of microelectronics as transparent conductors and active elements in chemical sensors. While forming different metallic contacts to these layers are required for different applications, noble metals are of particular use in gas sensor fabrication as these devices operate at elevated temperatures and harsh environments. The background literature on the quality and electronic features of gold and silver contacts on SnO₂ layers is limited. Moreover, it has been shown that both gold and silver electrodes exhibit different electronic features on TiO₂ at different thermal and atmospheric conditions. Here, we report the I-V characteristics of Au/SnO₂ and Ag/SnO₂ contacts formed on SnO₂ layers deposited on SiO₂ substrates by ultrasonic spray pyrolysis. The obtained I-V plots proved the ohmicity of the Au/SnO₂ and Ag/SnO₂ contacts to be independent from the temperature, in the range of 300-700 K, and the composition of the surrounding atmosphere.

Abstract: The paper will present a review of different solutions for transparent conducting electrodes on flexible substrates. The analysis of the present situation reveals a gap for low sheet resistance electrodes. Two new approaches to the problem will be presented. The first one is a novel technology for the deposition of zinc oxide on polyethylene terephtalate film. The intention for this process is the establishment of a low cost coating in a roll-to-roll machine. Silicon was used as the dopant material with a concentration varying in different samples between 1 and 4 %. The optimum parameters provided a transparent layer with a sheet resistance of 16 Ωsqu. Metal grids are a second promising approach for achieving low sheet resistance electrodes. The combination of these grids with transparent conducting oxides (TCO) will be presented. The TCO were deposited under vacuum in a roll-to-roll coating machine. The grids were applied by aerosol jet printing and subsequent tempering of the film.

Abstract: Thin films of Au were made by sputter deposition onto glass substrates with and without transparent and electrically conducting layers of SnO2:In. The Au films were up to ~11 nm in thickness and covered the range for thin film growth from discrete islands, via large scale coalescence and formation of a meandering conducting network, to the formation of a more or less “holey” film. Scanning electron microscopy and atomic force microscopy showed that the SnO2:In films were considerably rougher than the glass itself. This roughness influenced the Au film formation so that large scale coalescence set in at a somewhat larger thickness for films on SnO2:In than on glass. Measurements of spectral optical transmittance and electrical resistance could be reconciled with impeded Au film formation on the SnO2:In layer, leading to pronounced “plateaus” in the near infrared optical properties for Au films on SnO2:In and an accompanying change from such two-layer films having a lower resistance than the single gold film at thicknesses below large scale coalescence to the opposite behavior for larger film thicknesses.

Abstract: ZnO:Al thin films were deposited on sapphire(001) substrates by RF magnetron sputtering. Effects of the O2/Ar flow ratio in the sputtering process on the crystallinity, surface roughness, carrier concentration, carrier mobility, and optical properties of the films were investigated. AFM analysis results show that the surface roughness is lowest at the O2/Ar flow ratio of 0.5 and tends to increase owing to the increase of the grain size as the O2/Ar flow ratio increases further than 0.5. According to the Hall measurement results the resistivity increases as the O2/Ar flow ratio increases. The transmittance of the film tends to increase as the O2/Ar gas flow ratio increases up to 0.5 but it nearly does not change with continued increases in the O2/Ar flow ratio. Considering the effects of the the O2/Ar flow ratio on the surface roughness, electrical resistivity and transmittance properties of the ZnO:Al film the optimum O2/Ar flow ratio is 0.5 in the RF magnetron sputter deposition of the ZnO:Al film.