Solution-processed Er-Doped GeS chalcogenide glass films with NIR photoluminescence towards functional flexibility and integration.

Rare-earth doped chalcogenide films are major components in flexible and integrated photonic and optoelectronic devices for modern communication systems, metrology, and optical sensing. However, it is still challenging to develop a high concentration of rare-earth doping chalcogenide film with a smooth surface to realize efficient photoluminescence (PL). Here, we demonstrate that Er-doped GeS films are prepared by spin-coating based on a two-step dissolution process. Such a two-step process provides the high solubility of Er in GeS films and exhibits efficient emission at ∼1.5 µm crossing the telecommunication C-band. The highest PL emission intensity is obtained in GeS films doped with 1.4 mol% of Er, and this PL in GeS films is reported for the first time. We propose adjustments of annealing parameters for improving the PL characteristics in such materials. Through the control precision of the heating rate and annealing temperature, the smooth surface of GeS films enables efficient photo-luminescence. This two-step dissolution-based strategy would pave a new path to design luminescent chalcogenide films for application in flexible and integrated optoelectronics and photonics.