C.F. Lin

Fabrication of InGaN/GaN nanorod light-emitting diodes with self-assembled Ni metal islands

We report the fabrication of InGaN/GaN nanorod light-emitting diodes (LEDs) using inductively coupled plasma reactive-ion etching (ICP-RIE) and a photo-enhanced chemical (PEC) wet oxidation process via self-assembled Ni nanomasks. An enhancement by a factor of six times in photoluminescence (PL) intensities of nanorods made with the PEC process was achieved in comparison to that of the as-grown structure. The peak wavelength observed from PL measurement showed a blue shift of 3.8 nm for the nanorods made without the PEC oxidation process and 8.6 nm for the nanorods made with the PEC oxidation process from that of the as-grown LED sample. In addition, we have demonstrated electrically pumped nanorod LEDs with the electroluminescence spectrum showing more efficiency and a 10.5 nm blue-shifted peak with respect to the as-grown LED sample.

Enhancement of light output power of GaN-based light-emitting diodes using a SiO(2) nano-scale structure on a p-GaN surface

GaN (gallium nitride)-based light-emitting diodes (LEDs) with a nano-scale SiO2 structure between a transparent indium-tin oxide (ITO) layer and p-GaN were fabricated. The forward voltage at 20 mA for a GaN-based LED with a SiO2 nano-scale structure was slightly higher than that of a conventional GaN-based LED because the total area of the p-type metal contact between the transparent ITO layer and p-GaN was smaller. However, the light output power for the GaN-based LED with a nano-scale structured SiO2 at 20 mA was 24% higher than that for a conventional GaN-based LED structure. This increase in the light output power is mostly attributed to the scattering of light from the SiO2 photonic quasi-crystal (PQC) layer.

Light-Output-Power Enhancement of GaN-Based Light-Emitting Diodes on an n-GaN Layer Using a

GaN-based LEDs with a SiO2 oxide PQC pattern on an n-GaN layer by nanoimprint lithography are fabricated and investigated. At a driving current of 20 mA on a Transistor-Outline-can package, the light output power of LED III (d = 1.2 μm) was enhanced by a factor of 1.20. The internal-quantum-efficiency result offers promising potential to enhance the light output power of commercial light-emitting devices with a SiO2 oxide PQC structure on an n-GaN layer.

\hbox{SiO}_{2}

Abstract: In this chapter, we discuss the flip-chip and thin-film types of GaN-based light-emitting diode (LED), which are used to produce devices with better light extraction efficiency and far-field distribution. Flip-chip LEDs (FCLEDs) with a micro-pillar array structure and FCLEDs with a geometric oblique sapphire structure are investigated. Thin-film LEDs (TFLEDs) are fabricated by a combination of wafer bonding and the laser lift-off technique, which are used to transfer the GaN epilayer to a more conductive substrate to give better thermal dissipation. GaN TFLEDs with a photonic crystal (PC) surface structure are demonstrated. This study examines the light extraction efficiency, directional far-field patterns and polarization properties of GaN PC TFLEDs.