Growth and Characterization of GeSn for Infrared Imaging

Student: Randy Quinde

Major Professor: Dr. Fisher Yu

Research Area(s):

Microelectronics

Photonics

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Background/Relevance

 

  • Current semiconductor material within infrared red (IR) devices are expensive for manufacturing and fabrication.
  • Growing group IV elements together, such as germanium tin (GeSn), within chemical vapor deposition (CVD) machines have could reduce the cost and improve the quality of IR devices.

Innovation

 

  • Implementing GeSn within today’s technology would greatly reduce the prices of cellphones, computers, and other everyday devices.
  • Lasing GeSn could improve the quality and speed of the internet as studies have shown.

Approach

  • Analyze and compare GeSn samples to find parameters of growth of GeSn on the UHV-CVD machine
  • Grow GeSn within Ultra High Vacuum- Chemical Vapor Deposition (UHV-CVD) by disbursing germane and tin tetrachloride into chambers
  • Find the thickness of the GeSn samples by using the VASE ellipsometer
  • Characterize the GeSn samples using photoluminescence (PL) and Raman spectroscopy to gather information on the sample’s quality, bandgap, strain, and crystallinity.

Key Results

  • GeSn was grown at 350oC, 1 torr, 25 sccm of argon(Ar), 10 sccm of germane (GeH4), and 0.02 sccm of tin tetrachloride at varying times.
  • Nucleation occurred between 20-25 minutes of growth of GeSn
  • Growth rate shows that 1 µm would take approximately 200 minutes.

Conclusions

 

  • The growth of GeSn in the UHV-CVD machine was successfully grown in the set parameters.
  • Growths performed with UHV-CVD  can now determine and control the thickness of material depending on the length of time.
  • Characterization results indicate the material had low tin (Sn) incorporation, direct bandgap energy, and low optical properties.
  • Research is still needed to study growth rate of GeSn at different temperatures, pressures, and flow rates for UHV-CVD machine.