We describe the microstructure and optical properties of near-ultraviolet InGaN-GaN light-emitting diodes (LEDs) fabricated onto conventional and patterned sapphire substrates (PSSs) using metalorganic chemical vapor deposition. The PSS LED with an optimized hole depth (1.5 μm) shows an improvement of the room-temperature photoluminescence intensity by one order of magnitude compared with that of the conventional LED. As much as a 63% increased light emission intensity of the PSS LED was obtained at a forward current of 20 mA. For a typical lamp-form PSS LED (at 20 mA), the output power and external quantum efficiency were estimated to be 10.4mW and 14.1%, respectively. The increase of the output power could be partly due to the improvement of the internal quantum efficiency upon decreasing the dislocation density, which was further confirmed by the transmission-electron-microscopy and etch-pit-density studies for the GaN-on-PSS samples. Moreover, the emitted light scattering at the GaN/PSS interface could also contribute to the enhancement of light extraction efficiency.
|Number of pages||4|
|Journal||Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers|
|Issue number||4 B|
|State||Published - 1 Apr 2005|
- Dislocation density
- Light-emitting diode
- Patterned sapphire substrate