Dependence of ozone concentration on the moisture barrier properties of aluminum oxide using atomic layer deposition

Abstract

As a thin film encapsulation method, atomic layer deposition (ALD) has the potential to provide superior protection for organic light-emitting diodes (OLEDs). However, the application of H2O and O2 plasma in the traditional ALD process has not yet resulted in a successful moisture barrier. The large dipole moment of H2O may result in excess residual hydroxyl groups, and the flux of charged particles from O2 plasma can damage organic materials. Here, we suggest the use of ozone (O3) as an alternative reactant to mitigate these limiting factors. It is a powerful oxidizer and is much more volatile than other oxidizing agents. Thus, O3 is a promising oxygen source to improve moisture barrier properties for OLEDs. This work describes the dependence of O3 concentration on the moisture barrier properties of Al2O3 thin films prepared by ozone-based ALD at 100 degrees C. Trimethylaluminum and O3 were utilized as aluminum and oxygen precursors, respectively. The O3 concentration varied from 100 to 400 g/m3 in increments of 100 g/m3. An increase in O3 concentration resulted in a significant enhancement in the moisture barrier performance of Al2O3, with values improving from 7.1 x 10(-)4 to 1.9 x 10(-)5 g/m2/day. Further characterization indicated that Al2O3 thin films produced at elevated O3 concentrations exhibited superior physical and chemical properties compared to those generated at lower O3 concentrations.