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Probing Electronic and Vibronic States in CdTe Self-Assembled Quantum Dots and CdS Nanowires using Room Temperature Resonant Raman Scattering

ABDI, AMENSISA B.
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1155833636

Abstract Details

2006, PhD, University of Cincinnati, Arts and Sciences : Physics.
Resonant Raman scattering (RRS) is a sensitive means to probe electronic and vibrational states in semiconductor nanostructures, even when such states are not accessible either through photoluminescence or transport techniques. In this thesis, resonant Raman scattering is used to probe the electronic and vibronic states of CdTe/ZnTe quantum dots and CdS nanowires at room temperature. In case of the CdTe/ZnTe quantum dots, the sensitivity of the ZnTe longitudinal optical phonon (LO) resonance is used to probe the excited state in the CdTe quantum dots. In addition, this technique is utilized to study the energy shifts due to post growth rapid thermal annealing. Due to annealing, both the ground and excited state energies of the quantum dots move to a higher value. This is consistent with the interdiffusion of Zn and Cd which makes the confining potential shallower and the average diameter of the quantum dots larger. In the case of the CdS nanowires, the 1-LO and 2-LO resonance is readily observed above the broad photoluminescence (PL) background. The lineshape of the integrated intensity of the 1-LO and 2-LO resembles the PL spectrum suggesting that the RRS probes the electronic states in both the ensemble and in single nanowires. In addition, the energy separation between the peaks of the 1-LO and 2-LO resonance of the ensemble CdS nanowires was found to be 34 meV which is comparable to the 37 meV value measured in bulk samples. We also show that spatially-resolved Raman scattering at resonance probes the structural uniformity in a single CdS nanowire and is able to identify the layers of the CdTe/ZnTe quantum dots sample. We found RRS intensity of single CdS nanowire strongly depends on the morphology of the wire. In conclusion, we have shown that RRS at room temperature is a sensitive and nondestructive tool to probe electronic and vibration sates as well as structural uniformity in semiconductor nanostructures.
Dr. Howard Jackson (Advisor)
141 p.
Physics, Condensed Matter

Recommended Citations

Citations

  • ABDI, A. B. (2006). Probing Electronic and Vibronic States in CdTe Self-Assembled Quantum Dots and CdS Nanowires using Room Temperature Resonant Raman Scattering [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1155833636

    APA Style (7th edition)

  • ABDI, AMENSISA. Probing Electronic and Vibronic States in CdTe Self-Assembled Quantum Dots and CdS Nanowires using Room Temperature Resonant Raman Scattering. 2006. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1155833636.

    MLA Style (8th edition)

  • ABDI, AMENSISA. "Probing Electronic and Vibronic States in CdTe Self-Assembled Quantum Dots and CdS Nanowires using Room Temperature Resonant Raman Scattering." Doctoral dissertation, University of Cincinnati, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1155833636

    Chicago Manual of Style (17th edition)

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This open access ETD is published by University of Cincinnati and OhioLINK.