Using Plasma Quest Limited’s thin film deposition technology, coatings of ZnS:Mn exhibiting strong photoluminescent characteristics have been deposited at low temperature. The low temperature nature of the HiTUS ZnS:Mn process makes it compatible with flexible displays, conformable lighting and indicator applications.
The intensity of light emission from HiTUS deposited ZnS:Mn thin films deposited at room temperature has been shown to be significantly higher than similar thin films deposited at elevated substrate temperatures and post deposition annealed using other sputtering technologies.
By increasing the flow rate of H2S for fixed target powers the films are seen to become highly transparent exhibiting an average visible (400 to 800 nm) transmission of approximately 90 % when referenced to an uncoated glass slide. The deposition rate is also seen to increase for constant target power with the introduction of more H2S gas into the process. This peaks at approximately 50 nm/min for a target power density of just 2.55 Wcm-2, with any further increase in partial pressure of H2S having a detrimental effect on the photoluminescent intensity. Deposition is carried out with no substrate heating or post annealing.
The thin film photoluminescent coatings have also been incorporated as the active light-emitting layer within thin film Electroluminescent devices deposited entirely using the HiTUS sputter deposition equipment.