Influence of ITO Substrate Surface and External Electric Field to Improve DR-1 Film Refractive Index Using PVD Method

Abstract

This research is aimed to study surfactant effect of ITO substrate and the effect of external electric field applied during the deposition process on properties of the resulted film. Further, the anchoring mechanism involved in the deposition of the molecule is investigated in relation with the properties of the fabricated film. In addition to that, the optical property of the film is also investigated to study the effect of the applied electric field. For those purposes, a special electric field assisted Physical Vapor Deposition (PVD) method has been developed allowing the deposition process to be carried out under varied electric field. The deposited molecular structure and orientation were characterized with SEM, FTIR and UV-Vis spectroscopic measurement. Based on these spectroscopic data, it is shown that anchoring mechanism with hydrogen bonding does occurred between DR-1 molecule and ITO substrate responsible of the stability of the fabricated film. The refraction index of the film has been measured by means of reflectometer. The result of this research, DR-1 films have been obtained which exhibit crystalline structure with the molecules deposited in parallel polar orientation perpendicular to the substrate and regular head to tail stacking when the electric field applied larger than 0.59 MV/m. This is understood to be result of the formation of strong hydrogen bonding acting as the anchoring mechanism. In addition, it is shown that increasing external electric field leads to increasing refractive index of the DR-1 films corresponding to the number of DR-1 molecules deposited perpendicularly parallel to the ITO substrate surface is greater.