Anisotropic crystallization in solution processed chalcogenide thin film by linearly polarized laser

TL;DR

This study investigates how linearly polarized laser induces anisotropic crystallization in arsenic sulfide thin films, revealing unique structural and optical properties distinct from thermal annealing.

Contribution

It demonstrates the effects of laser irradiation on atomic structure and photoluminescence, highlighting differences from traditional thermal processing in chalcogenide materials.

Findings

Laser irradiation causes atomic rearrangement and bond conversion.

Laser-processed films show polarization-dependent photoluminescence.

Distinct subwavelength ripples are observed in laser-crystallized films.

Abstract

The low activation energy associated with amorphous chalcogenide structures offers broad tunability of material properties with laser-based or thermal processing. In this paper, we study near-bandgap laser induced anisotropic crystallization in solution processed arsenic sulfide. The modified electronic bandtail states associated with laser irritation lead to a distinctive photoluminescence spectrum, compared to thermally annealed amorphous glass. Laser crystalized materials exhibit a periodic subwavelength ripples structure in transmission electron microscopy experiments and show polarization dependent photoluminescence. Analysis of the local atomic structure of these materials using laboratory-based X-ray pair distribution function analysis indicates that laser irradiation causes a slight rearrangement at the atomic length scale, with a small percentage of S-S homopolar bonds converting to As-S heteropolar bonds. These results highlight fundamental differences between laser and thermal processing in this important class of materials.