III-V inverse quantum dots fabrication, characterization and application
The quantum dot offers carrier confinement in three dimensions. It is expected to improve performance of photonic devices. However, quantum dot fabrication still requires significant quality improvement such as high uniformity and location controllability to be commercialized. In this thesis, the inverse quantum dot is presented as an alternative solution to enhance the quality of conventional quantum dots. The theoretical analysis shows that the inverse quantum dot can be tuned from quantum well to quantum dot like behavior by decreasing the pitch and increasing the diameter of pores. The inverse quantum dots are made with four basic processing steps: base structure growth, dielectric film patterning, etching, and regrowth. Electron beam lithography is used to increase the uniformity of the dots. Scanning electron microscopy shows the highly ordered pores compared to self-assembled quantum dots. The photoluminescence characterization shows the increased intensity compared to quantum well. Also, the quantization effect in the photoluminescence characterization shows the quantum dot like phenomenon. Diblock copolymer lithography and anodic aluminum oxide transfer are used to fabricate large area dot patterning. In diblock copolymer lithography, pore diameter and pitch are approximately 17 nm and 37 nm respectively. In anodic aluminum oxide transfer, pore diameter and pitch were approximately 140 nm and 500 nm respectively. These two techniques indicate their capability in performing large area quantum dot and inverse quantum dot fabrication.
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign