Plasma enhanced pulsed laser deposition (PE-PLD), is a novel thin film deposition technique, which utilises both laser produced and radio frequency (RF) plasmas, in order to deposit semiconducting, metal oxide thin films. In PE-PLD, a pure metal target is ablated within the environment of a RF inductively coupled plasma, which generates reactive oxygen species that react with the laser produced plasma, forming oxides that deposit onto a substrate. Metal oxides of interest within this work are copper oxides (CuO, Cu2O) and zinc oxide (ZnO), both of which are wide band-gap semiconductors, with applications in photovoltaics, electronic displays, batteries, and more. PE-PLD has shown promise in the deposition of metal oxides, with the RF plasma lending additional control over film growth, no need of substrate heating or film annealing, and the deposition of films on flexible plastic substrates.
Characterisation of both the laser ablated and RF plasmas will be presented in this work; laser ablation of metal and metal oxide targets has been modelled using the code POLLUX, showing that the compound nature of the oxide targets results in volatile ablation under the conditions used in PE-PLD. Whereas metal targets ablate in a much more stable and controlled manner.
Plus, gas temperature measurements of the RF plasma have been performed via complimentary diagnostic techniques, and the effect of pulsed operation on the gas temperature. Additionally simulations via the use of the code HPEM, have been used to characterise the importance of processes, such as heat transfer to reactor walls.
Lastly, analysis of films deposited by PE-PLD has been performed, showing ZnO, Cu2O and CuO films of uniform density across their entire depth, as well high density planes of ZnO, on both SiO2 and Si substrates, and the successful deposition of Al2O3 films on steel substrates, and semiconducting films on polymer substrates.
