Daniel R. Esposito


This poster reflects research conducted as part of a course project designed to give students experience in the research process.



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Quantum Dot Formation Using Nano-patterned Planar InAs D. R. Esposito, S. Elhamri Department of Physics, University of Dayton, Dayton, Ohio 45469 K. G. Eyink, J. Shoaf, V. Hart, L. Grazulis, K. Mahalingam, J. Hoelscher, M. Twyman, D. Tomich Air Force Research Laboratory, Materials & Manufacturing Directorate, Wright-Patterson Air Force Base, Ohio 45433, USA Abstract We are working to control the size and uniformity of quantum dots for applications requiring the fine tuning of their energy band gaps. The critical quantum dot nuclei size is determined through a balance of surface and bulk free energies. These quantum dot nuclei are formed randomly over the surface in space and time. We are developing a process which uses planar InAs and nano-patterning to fabricate quantum dots on the surface. By nano-patterning samples, we can bypass the nucleation process and form volumes of material which are larger than the critical nuclei size. Subsequent annealing under high arsenic overpressure will ideally allow the material to reorganize into an equilibrium geometry without dislocations. Quantum dot formation under this method is primarily driven by the reduction of dislocations which contribute to the strain of the material. Our experiments have shown that quantum dots tend to form in the squares of the patterned grid as expected. While they tend to be more uniform than randomly nucleated dots, the annealing process also subjects them to coarsening and evaporation. We are now trying to hydrogen radical clean and anneal the samples at lower temperatures in order to reduce the effects of these processes, which increase size variation and decrease total volume respectively.

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Said Elhamri

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Stander Symposium project

Research exercise: Quantum Dot Formation Using Nano-patterned Planar InAs