Date of Award
Bachelor of Science (BS)
Chemistry and Biochemistry
Dr. Alison R. Noble
A nanoscale interdigitated electrode array (IDEA) was successfully fabricated on a zinc selenide (ZnSe) substrate using a positive resist lithography process. A ZnSe surface cleaning method was developed in the process of establishing a reproducible technique for IDEA patterning. A bilayer resist consisting of the lift-off-resist LOR5A and the photoactive resist SPR-3012 was utilized to establish an IDEA pattern with high structural integrity. The patterned ZnSe was used for electrooptical studies of 4-cyano-4'-pentylbiphenyl (5CB) reorientation. Polarized microscopy and transmission FT-IR studies were performed to confirm the efficacy of our electrodes and to elucidate the Fréedericksz transition induced by the application of static voltages to the electrooptical cell. A new electrooptical cell design was implemented to enable polarized microscopy studies while maintaining compatibility with the previous set-up used for IR studies. The difference spectra obtained from FT-IR study suggests that the 5CB molecules were on average initially titled off the surface normal and were increasingly reoriented away from the direction of the surface normal as voltage was applied. Polarized microscopy studies show that maximal transmission occurs around 12 V, where voltage-induced electric fields effect a desirable twisting motion of 5CB molecules. This study thus shows an effective IDEA fabrication procedure and its useful application in the study of confined nanoscale liquid crystal orientation.
Tay, Nicholas Eng Soon, "Fabricating a Nanoscale Electrode Array on Zinc Selenide for Studies of Long-chain Alkanethiol Monolayer Influence on Liquid Crystal Orientation" (2014). Honors Projects and Presentations: Undergraduate. 210.