Quantitative determination of external and spontaneous quantum efficiencies in SiGeSn/GeSn quantum wells using Lambertian-referenced photoluminescence

GeSn quantum wells (QWs) are promising active regions for monolithically integrated group-IV mid-infrared light emitters, yet their radiative efficiency has not been quantitatively established because of the lack of a reproducible, system-independent measurement methodology. Here, we systematically determine the external quantum efficiency (EQE) and spontaneous emission quantum efficiency (SQE) of SiGeSn/GeSn single-and double-quantum-well (SQW and DQW) structures using a Lambertian-referenced photoluminescence technique. By combining calibrated EQE measurements with a photon extraction and recycling model, the intrinsic SQE is quantitatively extracted, enabling direct comparison across different material systems and experimental platforms. Temperature-and excitation-dependent measurements (10-300 K, 5-200 mW) reveal peak EQE/SQE values of 14.7%/85.9% for the SQW and 19.8%/89.7% for the DQW at 10 K, representing a substantial improvement over a previously reported GeSn QW reference sample measured under identical calibration conditions. The consistently high efficiencies obtained from independently fabricated SQW and DQW structures confirm the reproducibility of the optimized epitaxial growth process and indicate significantly improved material quality.