Modeling the Sputter Deposition of Thin Film Photovoltaics using Long Time Scale Dynamics Techniques

ABSTRACTResults are presented for modeling the deposition of Ag and rutile TiO2. The model can be used to examine the effect of varying experimental parameters, such as the substrate bias in the magnetron and the stoichiometry of the deposition species. We illustrate how long time scale dynamics techniques can be used to model the process over experimental time scales. Long time dynamics is achieved through an on-the-fly Kinetic Monte Carlo (otf-KMC) method, which determines diffusion pathways and barriers, in parallel, with no prior knowledge of the involved transitions. Using this otf-KMC method we have modeled the deposition of Ag and TiO2 for various plasma deposition energies, in the range 1 eV to 100 eV. It was found that Ag {111} produces the most crystalline growth when deposited at 40 eV. TiO2 growth showed that at energies of 1 eV and 100 eV a porous structure occurs with void formation. At deposition energies of 30 eV and 40 eV, a more dense and crystalline rutile growth forms. The results show that deposition energy plays an important role in the resulting thin film quality and surface morphology.