Strain Engineered Electrically Pumped SiGeSn Microring Lasers on Si

SiGeSn holds great promise for enabling fully group-IV integrated photonics operating at wavelengths extending in the mid-infrared range. Here, we demonstrate an electrically pumped GeSn microring laser based on SiGeSn/GeSn heterostructures. The ring shape allows for enhanced strain relaxation, leading to enhanced optical properties, and better guiding of the carriers into the optically active region. We have engineered a partial undercut of the ring to further promote strain relaxation while maintaining adequate heat sinking. Lasing is measured up to 90 K, with a 75 K T0. Scaling of the threshold current density as the inverse of the outer circumference is linked to optical losses at the etched surface, limiting device performance. Modeling is consistent with experiments across the range of explored inner and outer radii. These results will guide additional device optimization, aiming at improving electrical injection and using stressors to increase the bandgap directness of the active material.

Automated summary

SiGeSn materials show great potential for mid-infrared applications. In this study, an electrically pumped GeSn microring laser based on SiGeSn/GeSn heterostructures is demonstrated. The ring shape allows for enhanced strain relaxation, leading to improved optical properties and carrier guiding. Partial undercutting of the ring further promotes strain relaxation while maintaining adequate heat sinking. Lasing is achieved at temperatures up to 90 K, with a T0 of 75 K. The scaling of the threshold current density with the inverse of the outer circumference is attributed to optical losses at the etched surface. The results of this study will guide further optimization of the device towards improving electrical injection and increasing the bandgap directness of the active material using stressors.