Molecule Beam Epitaxy of GeSn on III-V material substrates for Photonic Applications

Student: Calbi Gunder

Degree: Ph.D., May 2022

Major Professor: Dr. Gregory Salamo

Research Area(s):



View Research Quadslide


  • Currently infrared imaging sensors are rather large and expensive which could be alleviated though research into GeSn incorporated on silicon a group IV material and other III-V substrates.
  • Germanium (Ge) has higher optical absorption efficiency in a range of interest between 1.3-1.6 μm wavelengths for near infrared applications however it has an indirect bandgap, but it can be manipulated to be direct through the incorporation of Sn.


  • Develop and understand the growth of GeSn through the use of MBE in order to better incorporate it into substrates.


  • Through the use of MBE (Molecular Beam Epitaxy), deposit epitaxial GeSn films on Ge substrates.
  • Apply this knowledge to deposition on Si and GaAs. In order to deposit on Si, may look at using a buffer layer such as Ge to reduce lattice mismatch.

Key Results

  • XRD data (left) shows a Sn content of 5.8% to 8.2% in the GeSn structure.
  • AFM (right) shows that some Sn segregation has occurred.


  • GeSn Sn segregation needs to be reduced.
  • More experimentation of increasing Sn content should be conducted.

Future Work

  • GeSn with Ge buffer layer should be investigated on Si.
  • Investigation into the reduction of Sn segregation.