Germanium Tin (GeSn)

- Germanium Tin (GeSn) is an alloy between pure Ge and Sn
- Adding Sn to the Ge lattice transitions pure Ge into a direct bandgap semiconductor
- Applications include: IR LEDs, LASERs and detectors for various communication applications

Germanium Tin Growth

- Advanced Epi can grow high quality GeSn (strained or relaxed) up to ~11% Sn content
- Advanced Epi grow GeSn alloys on relaxed Ge buffers grown on Si(100) substrates with buffer thicknesses typically 600-1000nm
- GeSn Epilayers can be grown on 100 or 150mm diameter substrates
- Electrically active doping is possible with both n-type (P) and p-type (B) dopants

Material Characterisation

Schematic2

Cross sectional schematic for GeSn epilayers grown on Ge buffers (virtual substrates).

XRD
AFM
TEM

X-ray diffraction (XRD) coupled scans of fully strained GeSn epilayers of 5% and 10% Sn composition.

The surface roughness of GeSn epilayers tends to increase with Sn content, thickness and relaxation although films with RMS roughness <2nm are possible.

Cross-sectional TEM image showing high quality GeSn epilayer grown on a relaxed Ge buffer.