Abstract
In this work, single crystalline GeSn on insulator (GSOI) were grown by rapid melting growth (RMG). The Sn content distribution along the strip was investigated, reaching to 7.8% near the end of the strip. The GeSn strip had high quality with no threading dislocations, as revealed by cross-sectional transmission electron microscopy (XTEM). Photoluminescence (PL) measurements along the strip were performed to check the indirect-direct bandgap transition Sn content of GeSn alloys. It was found the integrated PL intensity increased about 6.6 times for Sn content 0.86%–7.8%. For GeSn with Sn content 6.1%, the temperature-dependent PL shows that the energy difference between direct Γ-Γ valley and indirect L-Γ valley decreases due to the bandgap narrowing (BGN) effect, and the direct band transition gradually dominates the PL spectra as temperature increases. The temperature-dependent PL spectra have only one peak for GeSn with Sn content 7.8%, suggesting the direct bandgap property. These results indicate that GeSn grown by RMG is very promising for fabricating efficient Si based light sources.
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