Joanna Millunchick

Professor

joannamm@umich.edu

2014 HH Dow

T: (734) 647-8980

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Self-Assembly of Compound Semiconductor Nanostructures: Directed Assembly of Quantum Dots using Focused Ion Beams (FIB)

Sponsor: National Science Foundation
Modification of materials such as InGaAs and GaAs through focused ion beams (FIB) may be useful in manufacturing nanoscale optoelectronic devices. The goal of this project is to integrate a UHV compatible FIB column arriving this November with our current MBE/STM system. Upon successful integration, a combination of MBE growth, FIB patterning, and STM will be used to create and study novel optoelectronic materials. Update: The FIB column has been sucessfully integrated with the existing MBE/STM. Initial experiments where GaAs buffer layers are grown and then patterned with the FIB followed by InAs growth are going well.
Highlights (Click an image for more information)
  • Steps on GaAs 1

    Tapping mode AFM image of GaAs surface after in vacuo annealing treatments and depostion of 2 ML of InAs. Field of view is 5 um. Sharply defined atomic steps and large smooth terraces are visable. A feature in the lower left quadrant of the image is likely a single InAs quantum dot.

  • Steps on GaAs 2

    Tapping mode AFM image of GaAs surface after in vacuo annealing steps and depostion of 2 monolayers of InAs. Field of view is 5 um. Sharply defined steps and large terraces are visable.

  • FIB induced Quantum Dots on GaAs

    Tapping Mode AFM image of patterned quantum dot sample. Field of view is 2 um. Following buffer layer growth, the surface was patterned in vacuo with a focussed ion beam. After patterning, the sample was re-introduced to the MBE chamber where 2.4 monolayers of InAs were deposited. On unpatterned areas, InAs quantum dots have nucleated randomly. However, on the FIBed regions larger islands have nucleated