Toshiba invests in Bridgelux to develop GaN-on-silicon LEDs

Toshiba and Bridgelux plan to develop GaN-on-silicon LEDs on 8-inch wafers, making use of Toshiba’s capabilities in silicon-based device manufacturing.

Toshiba, the Japan-based industrial giant and lighting manufacturer, has made an equity investment in Bridgelux, the Livermore, California-based LED maker. The companies have also reported impressive results from GaN-based LEDs fabricated on 8-inch silicon wafers.

Toshiba said that the investment was made “with the intent to jointly pursue an innovative technology in the solid-state lighting space.” Specifically, the companies are planning to boost Bridgelux's GaN-on-silicon LED chip technology development efforts by making use of Toshiba's advanced silicon process and manufacturing technology capabilities.

Toshiba and Bridgelux engaged in a joint collaborative agreement earlier this year. Bill Watkins, CEO of Bridgelux, said: "Toshiba and Bridgelux have already been engaged in the development of the technology, and the equity investment brings both companies one step closer to a more strategic relationship and achieving our shared goal of driving down the cost of solid-state solutions for the general lighting market."

The companies also reported results of their joint development. GaN-based blue LED chips fabricated on 8-inch-diameter silicon wafers demonstrated an optical power of 614 mW with a forward voltage of 3.1V when driven at 350 mA. The chip size was 1.1x1.1 mm.

"We are pleased to achieve the best-reported 8-inch GaN-on-silicon LED performance through our joint development activities with Bridgelux. We will continue to pursue more advanced development targeting commercialization of the technology," said Makoto Hideshima, Executive VP of Semiconductor and Storage Products Company and Corporate VP of Toshiba.

Companies pursuing the development of GaN-on-silicon LEDs believe this technology could ultimately lead to a significant cost reduction for LED chips, due to the large size and low cost of silicon wafers. When reporting R&D results from GaN-on-Si LEDs in August 2011, Bridgelux said that this approach could ultimately yield a 75% improvement in cost for LED components.

Other companies including Osram Opto Semiconductors are also working on the GaN-on-silicon approach. In January 2012 this year, Osram showed optical power results of 634 mW at 3.15V for 1.0x1.0-mm chips at 350 mA. However, these chips were fabricated on 6-inch wafers (see Osram Opto unveils R&D results from GaN LEDs grown on silicon).

Toshiba is a major lighting manufacturer in Japan and has also introduced LED-based lamps and fixtures into the US and European markets. Some of Toshiba’s LED lamps already use the company’s own LEDs, and that the company plans to become more vertically integrated in the future. The amount received by Bridgelux from Toshiba was not specified, but in February 2012 the California-based company secured an investment of $25 million from Kaistar Lighting.

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