122 TECHNOLOGY / LED
FIRST GALLIUM-NITRIDE LED CHIPS ON SILICON IN PILOT STAGE OSRAM Opto Semiconductors expands its leading position in high-quality, thin-film LEDs.
process of artificial crystal growth (epitaxy), the foundation for this milestone in the development of new manufacturing technologies. The German Federal Ministry of Education and Research funds these activities as part of its “GaNonSi” project network.
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. Already in the pilot stage, the new LED chips are to be tested under practical conditions, meaning that the first LEDs on silicon from OSRAM Opto Semiconductors could hit the market in just two years. “Our investments in years of research are paying off, because we have succeeded in optimizing the quality of the gallium-nitride layers on the silicon substrates to the point where efficiency and brightness have reached competitive market levels. Stress tests we’ve already conducted demonstrate the high quality and durability of the LEDs, two of our traditional hallmarks,” says Dr. Peter Stauss, project manager at OSRAM Opto Semiconductors. The company has acquired comprehensive expertise over the last 30 years in the
ADVANTAGES OF SILICON 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. “For these LEDs to become widely established in lighting, the components must get significantly cheaper while maintaining the same level of quality and performance,” Stauss emphasises. “We are developing new methods along the entire technology chain for this purpose, from chip technology to production processes and housing technology.” Mathematically speaking, it is already possible today to fabricate over 17,000 LED chips of one square millimeter in size on a 150 millimeter wafer (6 inch). Larger silicon wafers could increase productivity even more; researchers have already demonstrated the first structures on 200 millimeter substrates (about 8 inches).
www.osram-os.com
of current thought processes often staid by conventional thought. Thankfully, the European Commission agrees and have recently published a Green Paper entitled ‘Lighting the Future: Accelerat- ing the deployment of innovative lighting technologies’. The green paper is aimed at a wide audience covering individual con- sumers and professional users, the lighting industry, the building and construction sec- tor, architects, lighting designers, electrical installers, municipalities, public authorities, civil society communities, professional as- sociations and all other relevant stakehold- ers involved or interested in the topic and it can be downloaded from the EC’s consulta- tion website at
http://ec.europa.eu/infor- mation_society/digital-agenda/actions/ssl- consultation/
index_en.htm. At the same time as the launch of the Green Paper the EC has started a period of industry-wide consultation from the 15th December 2011 until 29th February 2012. The objective of the consultation is to seek the views of all interested individuals and organisations on the relevant issues involved by collecting replies on specific questions set out within the Green Paper.
To this end, the Green Paper proposes to launch a number of new policy initiatives and a public debate in Europe for acceler- ating the wide deployment of innovative high-quality lighting solutions, which are based LED and organic LED technologies also commonly referred to as ‘Solid State Light- ing’ (SSL). The Green Paper addresses both the demand and supply side. The Green Paper first addresses policies targeting European users (professional users and consumers) for overcoming existing challenges for wider market uptake. It then proposes policies addressing the European lighting industry with the aim to foster its leading position and competitiveness thus contributing to the creation of growth and jobs in Europe.
For example, on the demand side (European users) the EC proposes to raise awareness and demonstrate to consumers, professional users and public procurers that SSL tech- nology is of high quality and saves energy and money over its long lifetime, helping Europe meet its energy efficiency targets, and propose new initiatives to prevent early market failure. Whilst on the supply side (European lighting industry) the EC pro-
poses, amongst other initiatives, a raft of policies that foster the competitiveness and global leadership of the lighting industry and contribute to the creation of growth and jobs in Europe.
Current market penetration of SSL in Europe is very low: the LED market share (in value) reached 6.2% in 2010. However several studies such as ‘Lighting the way: Perspec- tives on the global lighting market’ by McKinsey & Company (2011) predict that SSL will account for more than 70% of Europe’s general lighting market by 2020. This af- fords a great opportunity to the European lighting industry with such a rapid growth rate in Europe over the next eight years and indeed I cannot think of any market that will have such strong demand in these timescales. The Green Paper highlights that lighting accounts for 50% of the electricity consump- tion of European cities and increasingly, cities are developing sustainable urban lighting strategies integrated with urban development policies and implemented in close cooperation with lighting designers, architects and town planners. The potential of SSL to become the replacement technol-
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