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

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.