Pore formation and removal in solution-processed amorphous arsenic sulfide films

This paper studies the formation of nanopores in solution-processed amorphous arsenic sulfide films and provides an effective method to remove such pores. Nanopores are observed mainly in the bulk of the film after being annealed above 120 C, and pore sizes are determined to increase with both baking temperature and duration. These observations are explained by a vacancy coalescence mechanism in the context of propylamine solvent. By adding a second solvent, ethylenediamine (EDA), to the original solution, we can essentially modify the material dissolution and annealing chemistry. Most pores are removed when 10% EDA is added, rendering a homogeneous film. The work presented here has great implications for improving the quality of optical chalcogenide components processed with solution methods. It also reinforces the pore formation mechanism that has been relevant to many solution-processed materials.