Development of aspect ratio trapping growth of GeSn on Si for midwave infrared applications

Abstract

The development of all-group IV GeSn materials on Si substrates is of interest for monolithic midwave infrared (MWIR) silicon photonics. Despite their great potential, the growth of high crystalline quality materials is still challenging. The conventional growth of GeSn films on Si displays high densities of dislocations and, hence, large dark currents. We have examined a state-of-the-art lithographically defined aspect ratio trapping (ART) growth approach for threading dislocations (TDs) filtering in GeSn and demonstrated the selective growth in the holes embedded in the SiO2/Si(001) template. While an exceptionally low density of TDs was confirmed by transmission electron microscopy imaging, we find that Sn incorporation is strongly suppressed in the ART-grown structures. Nonetheless, these results provide a solid basis for further efforts to enhance the Sn fraction of the GeSn ART growth.