Electrical Transport Measurements of Graphene on CdPS3

Student: Tony Dorhauer

Major Professor: Dr. Uche Wejinya

Research Area(s):

Nanoscale Materials & Devices

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Background/Relevance

  • Graphene is very thin, 2-Dimensional layer of graphite, organized in a hexagonal pattern on the atomic scale
  • Graphene has great electrical, chemical, and thermal properties
  • Graphene has very high electrical conductivity

Innovation

  • Try to understand how electrical properties affect sensing parameters

Approach

  • Clean the chip, apply the resist (PMMA)
  • Electron Beam Lithography (EBL) etches the design onto the chip
  • Metal evaporation coat the design in gold
  • Bond wires onto the wire contacts
  • Flake transfer to put graphene onto the back gate
  • Anneal the device and, if necessary, plasma etch as a final clean
  • Finally, the device undergoes a Hall experiment at temperatures close to absolute zero in the cryostat

Key Results

Hexagonal Boron Nitride (hBN)

  • Carrier Density: n = 2.518*1012 cm-2
  • Electron Mobility: µ = 286 cm2/Vs

Cadmium Phosphorus Sulfide (CdPS3)

  • Carrier Density: n = 1.774*1013 cm-2
  • Electron Mobility: µ = 164 cm2/Vs

*discrepancy over mobility values due to an inaccuracy of magnetic field value

Conclusions

  • No conclusive evidence to support either substrate being better than the other

  • Boron nitride had a greater mobility

  • Cadmium phosphorus sulfide had a higher carrier density

  • Further testing must be done