The New Jersey Institute of Technology's
Electronic Theses & Dissertations Project

Title:	Optical engineering of iii-nitride nanowire light-emitting diodes and applications
Author:	Bui. Ha Quoc Thang
View Online:	njit-etd2021-001 (xxiii, 137 pages ~ 3.5 MB pdf)
Department:	Department of Electrical and Computer Engineering
Degree:	Doctor of Philosophy
Program:	Electrical Engineering
Document Type:	Dissertation
Advisory Committee:	Nguyen, Hieu Pham Trung (Committee chair) Misra, Durgamadhab (Committee member) Sosnowski, Marek (Committee member) Zhou, Tao (Committee member) Voronov, Roman S. (Committee member)
Date:	2021-05
Keywords:	GaN III-Nitrides Light-emitting diodes Micro-LED displays Narrow band LED Phototherapy
Availability:	Unrestricted
Abstract:	Applications of III-nitride nanowires are intensively explored in different emerging technologies including light-emitting diodes (LEDs), laser diodes, photodiodes, biosensors, and solar cells. The synthesis of the III-nitride nanowires by molecular beam epitaxy (MBE) is investigated with significant achievements. III-nitride nanowires can be grown on dissimilar substrates i.e., silicon with nearly dislocation free due to the effective strain relaxation. III-nitride nanowires, therefore, are perfectly suited for high performance light emitters for cost-effective fabrication of the advanced photonic-electronic integrated platforms. This dissertation addresses the design, fabrication, and characterization of III-nitride nanowire full-color micro-LED (μLED) on silicon substrates for μLED display technologies, high-efficient ultraviolet (UV) LEDs, and spectral engineering for narrow band LEDs. In this dissertation, InGaN/AlGaN nanowire μLEDs were demonstrated with highly stable emission which can be varied from the blue to red spectrum. Additionally, by integrating full-color emissions in a single nanowire, phosphor-free white-color μLEDs are achieved with an unprecedentedly high color rendering index of ~ 94. Such high-performance μLEDs are perfectly suitable for the next generation high-resolution micro-display applications. Moreover, the first demonstration of two-step surface passivation using Potassium Hydroxide (KOH) and Ammonium Sulfide (NH4)2Sx is reported. The photoluminescence, electroluminescence, and optical power of the 335 nm AlGaN nanowire UV LEDs show improvements by 49%, 83%, and 65%, respectively. Such enhanced performance is attributed to the mitigation of the surface nonradiative recombination on the nanowire surfaces. A combination of KOH and (NH4)2Sx treatment shows a promising approach for high efficiency and high power AlGaN nanowire UV LEDs. The LEDs with narrow spectra are highly desirable light sources for precisely controlled applications such as phototherapy. In this regard, we have further demonstrated narrow spectral nanowire LEDs using on-chip integrated bandpass filters. To achieve narrow band spectra, the bandpass filters are designed and fabricated using all-dielectric and metal-dielectric multilayers for visible and UV regions, respectively. They are fabricated onto LED devices as a single photonic platform to achieve the narrow band LEDs for innovative applications like phototherapy for wound healing.