Deposition schemes for low cost transparent conductors for photovoltaics

Production requirements for transparent conductors for thin film photovoltaics are reviewed, with particular reference to magnetron sputtered zinc oxide. On-going optimization processes for ZnO:Al prepared on 0.43 m(2) substrates by bipolar, reactive sputtering from ZnO:Al2O3 targets and by reactive sputtering from a Zn:Al target are described. Optical emission from the plasma is used to study the state of the sputtering target. Attention is drawn to the spatial dependence of deposition conditions under the cathode.