ABSTRACT
This chapter presents a simple yet powerful two-photon fluorescence imaging technique for minimally invasive evaluation of the gallium nitride-based structure deep within a micro-light-emitting diodes (LED) array. By exciting the GaN-based heterostructure via two-photon absorption, the resulting fluorescence can be used to generate optical sections of the active medium within the sample. In particular, the progress of wide-bandgap nitride-based blue LED has considerably expanded the operational spectral range of semiconductor devices, leading to a shift in research focus towards the fabrication of higher power and higher efficiency LEDs. The micro-devices were fabricated on an LED wafer grown on the plane of a sapphire substrate. High-performance GaN/InGaN individually addressed micro-LED arrays have been imaged using two-photon microscopy. In the case ofinGaN/GaN micro-LEDs, the novel approaches adopted include the application of pattern-etching, where arrays of isolated pillar-like micro-size LEDs are formed, sharing a common broad-area metallisation.
