Using photonic crystal structure GaN based LED luminous flux increased by 42%

Alps Electric has developed a photonic crystal structure, will increase the luminous flux of about 42% of the class LED, and in the "ALPS SHOW" (September 2008 ~ 26 ~ 25) on display on the "GaN". The luminous wavelength is 510.7nm, the color is bluish green. On the surface of LED, the diameter of 800nm and the depth of 750nm were set at the 1000nm space, and the photonic crystal structure was formed. The forward current is 20mA and the flux is 1.41lm when the +3.8V voltage is applied. When the photonic crystal structure is not used, the same voltage is only 0.99lm. LED chip size is 0.35mm x 0.7mm x 0.1mm thick. Photonic crystal part of which the size of 0.2mm * 0.2mm.

When the photonic crystal structure is not used, the luminous wavelength is 520.5nm, the wavelength of the structure is shortened by about 10nm. This is because the photonic crystal structure of the LED, the current concentration in the light-emitting layer region, affected by the wavelength of light to the wavelength shift.

The photonic crystal structure is embedded in the LED structure of 4 inch (100mm) substrate (substrate material for sapphire) on the surface of the electron beam irradiation processing. After processing, the chip is cut from the bottom plate. By optimizing the diameter, depth and distance of the hole, the luminous flux can be increased to 2 times.

Figure 2: luminous LED. The left side of the photonic crystal structure, the right side of the photonic crystal structure

In order to achieve practicality in 2009, the Alps are promoting the development of. The procurement is embedded in the LED structure of the substrate, and then embedded in the bottom of the photonic crystal structure. The company intends to first process the luminous efficiency of the recognized lower green LED to enhance the brightness as a selling point to launch products.

Source: Nikkei BP