Morphological anisotropy of nano-dimensional arsenic trisulfide glass films and liquid crystal photoalignment

ABSTRACT

The results of high-resolution x-ray reflectivity study of nano-dimensionally thin arsenic trisulfide (As₂S₃) glass films reveal surface roughness anisotropy upon prolonged irradiation with polarized 436 nm blue light. The anisotropy correlates with the photoinduced anisotropy and LC photoalignment observed on these thin films. However, the As₂S₃ film's thickness reduces drastically during the reflectivity experiments, and ambient oxygen and moisture penetrate the film and create a second altered thin layer on top of a thicker film of As₂S₃. The results confirm the viability of As₂S₃ films for non-contact LC photoalignment material but suggests the need for further process optimization to reduce the films' degeneration to increase their effectiveness.

KEYWORDS:

• Photoalignment
• liquid crystal
• chalcogenide glass
• X-ray reflectivity

Funding

A. C. and T. A. K. acknowledge the Planning and Budgeting Committee of the Council for Higher Education of Israel for Post-Doctoral fellowship. X-ray work performed at Kent State University was supported by the US-Israel Binational Science Foundation grant 2012123 and by the US Ireland R&D Partnership program of the National Science Foundation award # DMR-1410649. The work at BGU is supported by the US-Israel Binational Science Foundation.