Abstract

Gallium Nitride (GaN) light emitting diodes (LEDs) are viewed as the next generation of display technology as a replacement for both liquid crystal displays (LCDs) and organic light emitting diode (OLED) displays. GaN based LEDs offer immense improvements in terms of efficiency, reliability, and resolution as compared to these conventional display technologies. New device opportunities are presented with the advent of LED displays, however there are a number of key challenges that also need to be addressed. Displays rely upon transistors in order to individually control the brightness of each color in a pixel. LED displays are no different, though there are no straightforward ways to pair transistors with LEDs. Furthermore, LEDs still leave room for improvement, suffering from poor p-type activation, single color emission, and inflexibility. Though with the promise of GaN LEDs, new integration approaches are realized here to overcome these limitations.

To address the challenge of transistors and LEDs, an innovative integration between LEDs and field effect transistors (FETs) has been demonstrated. The integrated LED-FET devices lead to dramatic increases in resolution, substantial decreases in processing steps, and considerable area savings. Device and simulation results are presented, with further scaling optimizations outlined.

The idea of full color integration has been a challenge for LEDs, where often multiple material systems are combined in order to realize these displays. Multiple materials translate to higher costs and lower resolution, as separate fabrication is performed to create these LEDs and then transfer the LEDs together. Monolithic approaches have been pursued, though necessitate the use of rare-earth materials. Instead, the structure of the LED is exploited in order to create the full range of LED colors from red to blue in a simple, efficient, monolithic format to demonstrate multi-color µ-LEDs.

Several novel devices and integration schemes are also presented that expand upon the existing device applications. Work developing a novel nanowire lift-off mechanism is presented which allows for both substrate reuse, as well as flexible devices. A capacitor-LED integration mechanism is demonstrated to enhance hole activation and utilization. AC operating LEDs are demonstrated through tunneling. Integration of high-power devices are additionally investigated for driving higher power LEDs. Together these breakthroughs provide a pathway for LED displays and beyond.

Library of Congress Subject Headings

LED lighting--Materials; Gallium nitride--Electric properties; Field effect transistors

Publication Date

4-22-2021

Document Type

Dissertation

Student Type

Graduate

Degree Name

Microsystems Engineering (Ph.D.)

Department, Program, or Center

Microsystems Engineering (KGCOE)

Advisor

Jing Zhang

Advisor/Committee Member

Kai Ni

Advisor/Committee Member

Parsian Mohseni

Campus

RIT – Main Campus

Plan Codes

MCSE-PHD

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