Bandgap Engineering of ZnO Transparent Conducting Films

Low resistivity and transparent Al doped ZnMgO films were deposited on glass substrates by a pulsed laser deposition system. For up to 32 atm% of Mg content, segregation of a MgO phase was not observed. The bandgap of these films could be widened to about 4 eV with increasing Mg content. The relation between bandgap and resistivity was found to be a trade-off; i.e. the larger the bandgap, the higher the resistivity. The maximum bandgap among films with an electrical resistivity of less than 10-3 Ω cm was 3.94 eV. The average optical transmittance of these films was more than 90 % for wavelengths λ between 400 and 1100 nm. The transmittance around λ = 330 nm was still 50 %.

High-Quality Transparent Conducting Oxide Films Deposited by a Novel Ion Plating Technique

A novel ion plating technique that has the attributes of both superb controllability of the high density plasma used as well as ion beam shape has been developed and applied to the deposition of transparent conducting oxides. The advantages of this technique include reduced ion damage, scale-up capability, in-plane uniformity, the use of low growth temperatures and fast deposition rates suggesting that the technique is very promising for a variety of applications such as solar cells and organic device fabrication. Gallium doped zinc oxide films have been deposited on glass substrates at 200°C. Resistivities as low as ρ∼2.7×10-4 Ω-cm with high transparency have been demonstrated. In addition, this technique has been successfully applied to large area deposition such as 65 cm × 55 cm-sized glass substrates.