Growth and Characterization of Group-IV thin films by PEUHV-CVD

Student: Joshua M. Grant

Degree: M.S., May 2020

Major Professor: Dr. Fisher Yu

Research Area(s):



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  • The increase in Sn content in Ge based films lowers the Γ valley energy level to allow a direct band gap material states.

  • Growth window is narrow with.

  • CVD offers high growth rates increasing throughput and reducing cost.


  • Use of gas mixing system for precise atomic ratio for improved compositional control and repeatability.

  • Design of insitu characterization tooling for improved understanding of growth mechanisms.


  • Growth of GeSn on Ge buffered Si to increase Sn incorporation by developing GeSn buffers to control strain for Sn compositional improvements.
  • Growth using gas mixing system for improved SnCl4/GeH4 ratio control.
  • Same day characterization of samples for faster research progress.

Key Results

  • Sn incorporation increases as growth temperature decreases.
  • Consistent and repeatable high quality buffer layers.
  • SiH4 flow rate dependent SiGe composition on sapphire.


  • No conclusions at this time.

Future Work

  • Growth refinement using gas mixing system.

  • Upgrade of CVD system to expand capabilities.