Unveiling Planar Defects in Hexagonal Group IV Materials

Recently synthesized
hexagonal group IV materials are a promising
platform to realize efficient light emission that is closely integrated
with electronics. A high crystal quality is essential to assess the
intrinsic electronic and optical properties of these materials unaffected
by structural defects. Here, we identify a previously unknown partial
planar defect in materials with a type I3 basal stacking fault and investigate its structural and electronic
properties. Electron microscopy and atomistic modeling are used to
reconstruct and visualize this stacking fault and its terminating
dislocations in the crystal. From band structure calculations coupled
to photoluminescence measurements, we conclude that the I3 defect does not create states within the hex-Ge and
hex-Si band gap. Therefore, the defect is not detrimental to the optoelectronic
properties of the hex-SiGe materials family. Finally, highlighting
the properties of this defect can be of great interest to the community
of hex-III-Ns, where this defect is also present.