Date of Graduation

8-2019

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Microelectronics-Photonics (PhD)

Degree Level

Graduate

Department

Microelectronics-Photonics

Advisor/Mentor

Gregory J. Salamo

Committee Member

Hameed Naseem

Second Committee Member

Shui-Qing Yu

Third Committee Member

Morgan Ware

Fourth Committee Member

Rick Wise

Keywords

indium nitride, InN, MBE, molecular beam epitaxy, QDs, quantum dots

Abstract

Over the last decade, the evolution of the global consciousness in response to decreasing environmental conditions from global warming and pollution has led to an outcry for finding new alternative/clean methods for harvesting energy and determining ways to minimize energy consumption. III-nitride materials are of interest for optoelectronic and electronic device applications such as high efficiency solar cells, solid state lighting (LEDs), and blue laser (Blu-ray Technology) applications. The wide range of direct band gaps covered by its alloys (0.7eV-6.2eV) best illustrates the versatility of III-nitride materials. This wide range has enabled applications extending from the ultraviolet to the near infrared. This study investigates the processes by which InN quantum dots (QDs) form through molecular beam epitaxy (MBE) growth in Nitrogen-Rich and Metal-Rich growth environments.

Structural characterization was performed using Atomic Force Microscopy. Statistical analysis was performed on both growth environments, Metal-Rich and Nitrogen-Rich, to observe changes in nucleation density, QD height and diameter, volume of InN, and the contact angle between the QDs and the growth surface. To further understand the growth environments, the system was analyzed as functions of growth temperature, deposition time, and deposition rate. Under Nitrogen-Rich growth environment, it was found that the growth of InN QDs follows typical Stranski-Krastinov (SK), heterogeneous nucleation theory. However, due to the existence of an excess indium adlayer, the Metal-Rich growth condition changes the development of the InN QDs. The results of this investigation are presented herein. A cursory investigation in the optical response of both growth environments was performed. The optical response was characterized through photoluminescence (PL) spectroscopy with a transition at 730 nm for Metal-Rich InN QDs using a two-step GaN capping procedure.

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