Ion Implantation Damage Recovery in GeSn Thin Films

Germanium-tin (GeSn) alloys are promising materials for infrared photonics due to their tunable direct bandgap and compatibility with silicon technology. However, implantation doping of GeSn layers to achieve more sophisticated doping profiles faces challenges, particularly in restoring crystallinity after ion implantation. In this work, we investigate the recrystallization of ion-implanted GeSn thin films through rapid thermal annealing (RTA) and laser annealing. We propose a model for Sn diffusion pathways that lead to surface segregation based on distinct surface segregation patterns in GeSn layers with varying degrees of amorphization. Our results demonstrate that RTA at 400 °C effectively restores the crystallinity for GeSn thin films with up to 10.7 at.% Sn composition, despite a small amount of Sn surface segregation, while 532 nm wavelength CW laser annealing at a threshold power density above 52 kW/cm ² also achieves recrystallization without Sn segregation. These findings contribute to understanding Sn segregation mechanisms and optimizing recrystallization conditions for GeSn after implantation, advancing its potential for infrared photonics applications.