Enhanced light output power of thin film GaN-based high voltage light-emitting diodes.

The characteristics of high-voltage light-emitting diodes (HVLEDs) consisting of a 64-cell LED array were investigated by employing various LED structures. Two types of HVLED were examined: a standard HVLED with a single roughened indium tin oxide (ITO) surface grown on a sapphire substrate and a thin-film HVLED (TF-HVLED) with a roughened n-GaN and ITO double side transferred to a mirror/silicon substrate. At an injection current of 24 mA, the output powers of the HVLEDs fabricated using a sapphire substrate and those fabricated using a mirror/silicon substrate were 170 and 216 mW, respectively. Because the TF-HVLED exhibited improved thermal dissipation and light extraction, it produced a greater output power than the HVLED fabricated using the sapphire substrate did.

GaN light emitting diodes with wing-type imbedded contacts.

A wing-type imbedded electrodes was introduced into the lateral light emitting diode configuration (WTIE-LEDs) to reduce the effect of light shading of electrode in conventional sapphire-based LEDs (CSB-LEDs). The WTIE-LEDs with double-side roughened surface structures not only can eliminate the light shading of electrode and bonding wire, but also increase the light extraction and light output power. Contrast to CSB-LEDs, a 79% enhancement of output intensity in the WTIE-LED was obtained at 100 mA injection current. Similarly, the output power of packaged WTIE-LEDs was enhanced 59% higher compared with the packaged CSB-LEDs at the same injection condition. Therefore, using the imbedded contact to reduce light shading would be a promising prospective for LEDs to achieve high output power.