Engineering downward-propagating threading dislocations for InP lasers laterally grown on 220 nm SOI.

Selective lateral epitaxy represents an excellent candidate for scalable integration of III-V lasers on SOI. However, in this approach, threading dislocations (TDs) inevitably propagate upwards to the III-V film surface and jeopardize the efficiency and reliability of epitaxial III-V lasers. Here, we made a paradigm shift by designing an approach forcing TDs to propagate downward and creating an InP membrane free of surface TDs. In contrast to InP grown on thick SOI platforms, we demonstrated large-dimension InP membranes on Si photonics 220 nm SOI platforms by meticulously engineering the growth conditions. We then fabricated sub-wavelength InP nanodisk lasers monolithically integrated on 220 nm SOI and achieved single-mode lasing and ultra-low threshold of 65.8 µJ/cm. These results pave the pathway for the seamless and dense integration of III-V lasers on the Si photonics 220 nm SOI platform.