Development and implementation of monolithic GaN uLED arrays for multifunctional optical systems

Rights statement
Awarding institution
  • University of Strathclyde
Date of award
  • 2021
Thesis identifier
  • T16133
Person Identifier (Local)
  • 201673333
Qualification Level
Qualification Name
Department, School or Faculty
  • Monolithic LED arrays comprising micron-sized pixels are rapidly maturing as a technology due to their high efficiency and modulation rates. When coupled with complementary metal-oxide semiconductor (CMOS) electronics, which offer high level spatiotemporal control, such devices are capable of communications based applications along with the ability to provide structured illumination based functionality. This novel 'smart display' technology opens up a range of potential new applications. This thesis describes the full development of such micro-LED arrays from initial design and fabrication through to implementation. By manipulating their fabrication process, highly customised devices can be created to accommodate the needs of a specialised setup or application scenarios. An example of this is the creation of n-contact devices and modifying the epitaxial structure of the array to allow for individually addressable pixels to better suit specific driving electronics. Devices such as these were developed and characterised. When compared to existing state-of-the art alternatives, these devices are shown to be either comparable with or to exceed them in terms of modulation rate and optical power output. In addition to modifying LED epitaxy to create novel applications, arrays of LEDs can also be implemented to create imaging systems capable of 3D imaging using only a single camera. This setup along with the steps taken to optimise the process is also detailed. Furthermore it includes the incorporation of a 3-dimensional tracking system, which can be used simultaneously with 3D imaging. Along with new technologies introduced by micro-LED arrays, they can also be used to improve existing technologies and even add additional functionality to them. This thesis documents the development of a maskless photolithography setup wherein the optical emission pattern of the micro-LEDs is controllable through CMOS drivers to implement a direct writing tool and replace the quartz masks, typically used in photolithography. The setup is shown to be capable of producing highly uniform photolithography defined structures of controllable width across a 16 x 16 grid where each coordinate is individually addressable. By synchronising the LED array's emission pattern with a motorised XYZ stage, continuous customisable directly written structures can be developed. Along with the photocuring components of the setup, an additional LED array was incorporated allowing for additional functionality through structured illumination. This comes in the form of the recognition, tracking and automated alignment to non-standardised alignment markers on a micrometre scale. Photocuring was performed whilst aligned to these markers while simultaneously tracking these markers to ensure the quality of fabricated structures.
Advisor / supervisor
  • Gu, Erdan
  • Dawson, Martin
Resource Type