Success in research: First gallium-nitride LED chips on silicon in pilot stage

Researchers at OSRAM Opto Semiconductors have succeeded in manufacturing high-performance prototypes of blue and white LEDs, in which the light-emitting gallium-nitride layers are grown on silicon wafers with a diameter of 150 millimeters. The silicon replaces the sapphire commonly used until now without a loss in quality.

This is a pioneering development for several reasons. On account of its widespread use in the semiconductor industry, the availability of large wafer diameters and its very good thermal properties, silicon is an attractive and low-cost option for the lighting markets of the future. Quality and performance data on the fabricated LED silicon chips match those of sapphire-based chips: the blue UX:3 chips in the standard Golden Dragon Plus package achieve a record brightness of 634 mW at 3.15 volts, equivalent to 58 percent efficiency. These are outstanding values for 1 mm² chips at 350 mA. In combination with a conventional phosphor converter in a standard housing – in other words as white LEDs – these prototypes correspond to 140 lm at 350 mA with an efficiency of 127 lm/W at 4500 K.

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