Adsorption of molecular layers on hydrophilic SiOxNy probed by DPI technique

Abstract

The AnaLight Quantum with a new vapour deposition setup and improved protocol has been used to study the self-organization of 5CB molecules deposited from their vapour phase onto a hydrophilic silicon oxynitride surface. Although slightly less accurate, the results are in good agreement with the previous study in terms of average orientation angle and thickness of the monolayer deposited (56.5° and 1.44 nm respectively). We also studied adsorbed water layers on the hydrophilic surface, and found that our setup allows to desorb only about 10% of the layers since those are strongly held by the hydrophilic surface with an ice-like structure. Therefore the importance of performing
more advanced studies on the topic has been raised, as these layers may have an influence on the deposition of liquid crystal molecules. Finally we got some performance data about the AnaLight Quantum whose temperature control appeared not to be fast enough to compensate external thermal perturbations. That raised the importance of thermo-optic effects in such a configuration since they get mixed with adsorption effects within the results. Also an asymmetrical beam expander has been designed in order to improve the optical setup of the instrument.