Defense Date


Document Type


Degree Name

Master of Science


Electrical & Computer Engineering

First Advisor

Prof. Ümit Özgür, Ph.D.

Second Advisor

Prof. Hadis Morkoç, Ph.D.

Third Advisor

Prof. Vitaliy Avrutin, Ph.D.

Fourth Advisor

Prof. Michael Reshchikov, Ph.D.


Efficient and robust blue InGaN multiple quantum well (MQW) light emitters have become ubiquitous; however, they still have unattained theoretical potential. It is widely accepted that “localization” of carriers due to indium fluctuations theoretically enhance their efficiency by moderating defect-associated nonradiative recombination. To help develop a complete understanding of localization effects on carrier dynamics, this thesis explores degree of localization in InGaN MQWs and its dependence on well thickness and number of wells, through temperature and power dependent photoluminescence measurements. Additionally, silicon-compatible, nontoxic, colloidally synthesizable 2-5 nm Ge1-xSnx alloy quantum-dots (QDs) are explored for potential visible to near-IR optoelectronic applications. While bulk Ge is an indirect gap material, QD confinement allows enhanced direct transitions, and alloying with Sn improves transition oscillator strengths. Temperature dependent steady-state and time-resolved photoluminescence reveal relaxation pathways involving bright/dark excitons and surface states in Ge1-xSnx QDs, showing their great potential for future use.


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