Bridgelux Raises Lumen Per Watt Performance of GaN-on-Si Based LEDs

Combining advances in growth of gallium nitride (GaN) layers on 8-inch silicon wafers with improvements in proprietary buffer technology and manufacturing, solid-state lighting company Bridgelux (News - Alert) has achieved a new breakthrough in the efficiency performance of GaN on silicon (GaN-on-Si) based light-emitting diodes (LEDs). The company claims to have broken its previous Lumen per Watt (Lm/W) record.

 As a result, Bridgelux said it has demonstrated LED performance levels comparable to today’s state-of-the-art sapphire-based LEDs. According to the developer, cool white LEDs showed efficiencies as high as 160 Lm/W at a CCT of 4350K. While warm white LEDs constructed from the GaN-on-Si chips delivered 125 Lm/W at a color temperature of 2940K and CRI (News - Alert) of 80.

Conventional LEDs are made using sapphire or silicon carbide substrates as the starting material. Both are more expensive than silicon. As a result, production costs have inhibited the widespread adoption of LED lighting in homes and commercial buildings, according to Bridgelux.

But growing GaN on larger, low-cost silicon wafers that are compatible with modern semiconductor manufacturing can deliver a 75 percent improvement in cost over current approaches, Bridgelux said. The company believes that its technology process has the potential to significantly drive down the cost of manufacturing LEDs and make them competitive to conventional white lighting technology.

In a statement, Steve Lester, Bridgelux chief technology officer stated, “The performance levels that we announced today are the highest Lm/W values yet published for GaN-on-Si and rival the best commercial LEDs grown on sapphire or silicon carbide (SiC).”

He added, “These achievements are a direct result of our investment in building a world-class team of Bridgelux materials scientists and chip design engineers with a strong focus on driving industry-leading epitaxial process technology. We are very pleased with the pace of our progress in this area, and we will continue to aggressively develop our GaN-on-Si processes in order to drive the migration of LED commercial production from sapphire to silicon substrates. Our first commercially available GaN-on-Si products remain on schedule for delivery to the market within the next two years.”

In terms of output power, encapsulated 1.5 mm blue LEDs emit 591 mW with wall plug efficiency as high as 59 percent at 350 mA, exceeding any published values, claimed Bridgelux.  The LEDs have very low forward voltage, 2.85 V at 350 mA, making them suitable for use at high current densities, the maker said.

“This new technological breakthrough is a direct result of Bridgelux’s continued investment in research and development combined with a singular focus on the needs of the solid state lighting market,” said Bill Watkins, Bridgelux CEO.

“This key innovation is a game-changer for the industry, delivering dramatic reductions in the up-front capital investment required for solid state lighting and thereby significantly increasing the rate of market adoption,” noted Watkins.

To meet global demand for solid-state lighting, the LED developer and manufacturer recently secured $60 million in series E round of financing, led by Craton Equity Partners, Southern California's leading clean tech private equity fund.  The company plans to use new funding to extend its leadership position in the solid state lighting market by accelerating research and development in key areas of strategic focus for the company.

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