GaN on silicon: A breakthrough technology for LED lighting (MAGAZINE)

Over the last decade, progress in light-emitting diode performance has been nothing less than phenomenal. LEDs today are performing at 50% wall plug efficiency, meaning that 50% of the applied power is emitted as light. Laboratory results are even higher in the high 60s; these results will become standard in due course. In the meantime, LED-based lighting is replacing incandescent, fluorescent, mercury, and sodium lamps in almost all applications. However, the uptake of LED lighting is still limited by the cost of producing LEDs. This one remaining barrier will be addressed by developments in gallium-nitride-on-silicon (GaN-on-Si) technology.

Shuji Nakamura developed a method of growing thin GaN layers on sapphire substrates in the early 1990s, and up to now these have been the foundation of high-brightness blue LEDs. One notable competitor is silicon carbide (SiC), but these substrates are very expensive. While sapphire costs are dropping, silicon is a very common substrate in the semiconductor industry, and the costs are much lower than either sapphire or SiC.

Semiconductors of all types are characterized by the spacing between atoms in the crystal lattice. One difficulty with using silicon as a substrate is that the atoms are not spaced at the same distance as the atoms in a GaN layer. Growing GaN directly on silicon would lead to a mismatch that would cause strain, and this strain would be relieved only through sporadic dislocations that in turn cause leakage currents and general impairment of the performance of the LED.

The breakthrough needed for growing GaN on silicon was to use a buffer layer that offers a better match to the silicon lattice, and then to gradually transpose the buffer layer into GaN. This buffer technology forms the basis of new GaN-on-Si technology. In addition to the buffer layer, considerable optimization has been pursued

Cree enters the LED MR16 lamp market with 92-CRI offering

Cree has announced LED-based MR16 lamps that operate from transformed 12-VAC input and deliver greater than 80% energy savings relative to legacy halogen lamps. The Cree MR16 Series TrueWhite LED lamp delivers 92 CRI and R9 saturated-red performance above 50 to meet demanding applications in hospitality and retail.

Cree enters the LED MR16 lamp market with 92-CRI offering

Cree notes that the MR16 sector is one area in which LED lamps haven’t performed commensurately with legacy lamps and that has limited LED success in the sector. The US Department of Energy (DOE) recently made the same points in a Caliper report on the sector.

The small form factor of MR16 lamps has been part of the problem with success in the sector. It’s difficult both to get the luminous punch and beam control required by applications such as retail and to fit in the required driver electronics. Still, LED lighting companies continue to chase the MR16 market because of the sheer number of sockets where the small lamps are used.

Apparently, the Cree design is largely drawing some interest from customers in the target application. “The Cree MR16 TrueWhite LED lamp is the best 50W halogen replacement lamp to combine the energy-saving benefits of LED with the light distribution and color quality our clients expect,” said Lee Mehler, principal architect and president of LMHT Associates/National Restaurant Designers. “We’ve been disappointed with other MR16 LED lamps on the market, but after testing the Cree MR16 Series TrueWhite LED lamp we are specifying and recommending the use of this product for new and retrofit projects to replace existing halogen MR16 lamps with Cree.”

Cree says that its design includes a light engine that can deliver 50 lm, and optics, including a proprietary lens, that eliminate the glare associated with many MR16 lamps.

Ikea venture group invests in Scottish manufacturer Design LED Products

Global home-furnishings retailer Ikea has announced that its European-focused Ikea GreenTech venture-capital unit invested in Design LED Products Ltd. The investment is intended to help the company deliver on its sustainability program called People & Planet Positive that is expected to help its customers adopt sustainable practices in their homes and save energy. This particular investment should result in unique LED luminaires that will be added to the Ikea portfolio.

Ikea venture group invests in Scottish manufacturer Design LED Products

Ikea has long championed sustainability and had said back in 2012 that it would transition all of its lighting products to LED sources by 2016. More recently, the company moved the goal forward to 2015, and the latest acquisition is surely intended to help the company deliver innovative luminaire products.

Design LED Products is a Scottish manufacturer of lighting tiles that are manufactured with optical resins and films and that have white LEDs integrated within the tiles. The tiles can be applied as sheet-like light engines in applications such as under-cabinet planar fixtures. The company also offers bendable tiles that could be used to enable unique form factors for solid-state lighting (SSL) products.

The concept of a flexible film or panel with integrated LEDs is not unique to Design LED Products. For example, startup Cooledge has presented their bendable panels at the Strategies in Light conferences and also won a LightFair Innovation Award in 2013. Thus far, however, the flexible panels have garnered much interest but the industry is waiting on innovative product to emerge based on the technology.

Ikea clearly sees potential in the light tile technology. “This technology opens up fantastic possibilities for innovative designs using energy-efficient LEDs,” said Christian Ehrenborg, managing director for Ikea GreenTech AB. “The partnership is a clear strategic fit for Ikea and our