Effect of plasma parameters on the properties of V2O5 deposited by plasma-enhanced atomic layer deposition

In this work, we investigate the deposition of VOx thin films by plasma-enhanced atomic layer deposition. Specifically, we focus on the effects of the plasma operating conditions, including applied power, O2/Ar gas flow ratio, pressure, and coupling mode on the resulting thin film crystallinity and stoichiometry. In addition, we characterize the plasma and correlate the findings to the changes observed in the produced VOx thin films. The majority of conditions investigated yield crystalline V2O5. However, by increasing the pressure during the plasma half cycle, the V2O5 film can be deposited with a reduction in the crystalline character without any significant changes in stoichiometry. Langmuir probe measurements reveal that both the ion flux and plasma potential decrease with increasing pressure during the plasma step, which results in a corresponding drop in the energy flux density and ion energy delivered to the surface of the thin film. Analysis of the various plasma conditions investigated shows that increasing the pressure uniquely resulted in a decrease in the energy flux density and ion energy below a critical barrier necessary for complete crystallization of the deposited VOx films.