(a) Cross-sectional schematic diagrams depicting architectures of (a) μLED, (b) tf-μLED, and (c) iso-μLED. Microphotographs showing emission from a group of pixels of the respective devices in (d)–(f). Cross-sectional emission intensity maps (142 × 1000 μm2 along x-z plane) of the respective devices plotted on linear scale (g)–(i) and logarithmic scale (j)–(l). Planar intensity maps of the respective devices plotted on logarithmic scale (m)–(o).
Applied Physics Letters, vol. 107, 17, pp. 171103 (2015)
The optical crosstalk phenomenon in GaN micro-pixel light-emitting diodes (LED) has been investigated by confocal microscopy. Depth-resolved confocal emission images indicate light channeling along the GaN and sapphire layers as the source of crosstalk. Thin-film micro-pixel devices are proposed, whereby the light-trapping sapphire layers are removed by laser lift-off. Optical crosstalk is significantly reduced but not eliminated due to the remaining GaN layer. Another design involving micro-pixels which are completely isolated is further proposed; such devices exhibited low-noise and enhanced optical performances, which are important attributes for high-density micro-pixel LED applications including micro-displays and multi-channel optical communications.
