Development of Critical Material and Device Technology for GeSn Based Integration

Student: Grey Abernathy

Degree: Ph.D., December 2021

Major Professor: Dr. Fisher Yu

Research Area(s):


View Research Quadslide


  • Photonics can provide an improved method for complicated signal processing  in conventional microwave applications.

  • Reduced SWAP at low cost is achieved when foundry manufacturing is available for photonic circuits on-chip.

  • The creation of integrated components (laser, modulator, etc.) is an integral addition for future microwave photonic circuits.


  • Incorporation of optical “on-chip” devices is considered to be paramount for the development of Photonic Integrated Circuits.
  • Wireless communications and defense RF applications can be achieved using a hybrid integration strategy for VCSELs.


  • Material growth-maturation is currently underway for the GeSn material system, as well as characterization for material properties.
  • UHV-CVD growth of GeSn on sapphire investigated and template development, as well as potential for sapphire waveguides.
  • Quantum well advancements display promise for active devices (lasers, detectors, etc).
  • A monolithic integration strategy for GeSn lasers with CMOS circuits will be explored.

Key Results

  • Developing and optimizing select component architecture.
  • Feasibility study of growing GeSn on sapphire.
  • Designing, developing, and evaluating optical waveguides for passive component creation.
  • Technology development for various device integration in microwave photonic circuits.


  • Using methods already established for optical circuit creation and modification, it will be possible to develop techniques for microwave photonic optical circuits.
  • The inclusion of CMOS compatible active components is an integral step in the creation of microwave photonic circuits to replace modern electronic microwave devices.

Future Work

  • Addition of more components with the proper arrangement and switching may be able to come closer to a realized Photonic Integrated Circuit.