Fig. 1. (a), (b) Cross-sectional TEM images of (a) GeSnOS and (b) GeSnOI substrates. Scale bar, 500 nm. (c) PL spectra from GeSnOI and GeSnOS substrates. The measurement temperature is 4 K.

Fig. 2. (a) Schematic illustration of the microdisk structure fabrication process. (b) Tilted-view SEM image of GeSnOI microdisk. Scale bar, 2 μm.

Fig. 3. (a), (b) Top views of simulated electric field distributions in the (a) GeSnOI and (b) GeSnOS microdisk structures, which achieve high-quality factors of >8000. Scale bar, 1 μm. (c), (d) Cross-sectional views of the same simulated electric field distributions in the (c) GeSnOI and (d) GeSnOS microdisk structures. Scale bar, 1 μm. (e), (f) Cross-sectional views of simulated thermal distributions in the (e) GeSnOI and (f) GeSnOS microdisk structures. Scale bar, 1 μm.

Fig. 4. (a), (b) PL spectra from (a) GeSnOI and (b) GeSnOS microdisks at different pump powers. (c), (d) Double-logarithmic L-L curves for (c) GeSnOI and (d) GeSnOS microdisks. Insets: linear L-L curves. (e), (f) FWHMs for (e) GeSnOI and (f) GeSnOS microdisks at different pump powers.