2009

Marubeni Concludes a Joint Agreement to Develop and Commercialize Next Generation White LEDs

Dec. 10. 2009
Marubeni Corporation


Marubeni Corporation (MARUBENI) concluded a contract with EL-SEED Corporation, a technology venture spun-off from Meijo University located in Nagoya, Aichi Prefecture, which has distinguished itself globally for its leading-edge research and development of nitride semiconductors and carbon nanotubes, to assist EL-SEED in commercialization of its Next-Generation White LEDs. The contract also calls for providing a certain amount of R&D funding.

The Next-Generation White LEDs under EL-SEED’s development  are formed in a very simple structure consisting of a specially doped, mono-crystalline silicon carbide (SiC) substrate capable of converting near UV light into a variety of white light, coupled with a near-UV LED attached to the SiC substrate. A small die, sized 1mm X 1mm, is able to emit very high  intensity white light on the order of wattage with an extremely high color rendering index close to sunlight.

Advantages of EL-SEED white LED’s over the currently-prevailing, so-called, pseudo-white LEDs (which are composed of a blue LED and yellow phosphors) include:

i)  Minimizing the deviation in color temperature by controlling the concentrations of
    dopants in SiC substrate, leading to a remarkably high production yield and significant reduction of yield loss.
ii)  Enabling a very high color rendering index (Ra) for pure white LEDs, close to sunlight.
iii) Achieving at least a five-fold prolonged life-span, resulting from the use of a highly heat-resistant and
    heat-dissipative SiC substrate which also functions as the means to convert near-UV light into white light.
    This simple structure enables significant cost reduction for Next Generation White LEDs and
    also enables elimination of both phosphors and plastic encapsulation,
which cause deterioration
    in the life-span and efficiency of pseudo-white LEDs due to the generated heat.

EL-SEED has already completed a manufacturing technique and process to produce a moth-eye structure (anti-reflective, finely-pitched, periodic corn structure discovered in the 1960’s) to drastically increase light extraction efficiency on such various substrates and materials as SiC, Sapphire, GaN, and ITO, with extremely high throughput and low cost. Coupled with highly reflective electrodes, also developed by EL-SEED, this combination of fluorescent SiC substrates and a moth-eye structure will offer high quality and low cost white LEDs.

MARUBENI has been fully committed to contributing to the reduction of greenhouse gas emissions by providing the necessary resources for emerging technologies, including LEDs and photovoltaic cells, to help minimize global warming and climate change.

About EL-SEED
Location:          Akasaki Institute, Nagoya University, 
                           Furo-cho, Chikusa-ku, Nagoya, Aichi Prefecture
President:         Tadao Kamiya
Paid-in Capital: JPY. 62,050,000 (approx. USD690,000)
Founded:          March, 2006
References:     In 2006, the moth-eye manufacturing technique for LEDs was selected
                        and funded by the Japan Science and Technology Agency (JST) as a
                        JST project to develop “Innovative Seeds”   
                        In 2009, Meijo University was selected as one of the “Leading-edge
                        Technology and Innovation Centers”, where EL-SEED plays an
                        important role in developing and commercializing 
                        “extremely energy-conserving, super color rendering indexed,
                        long life, and low cost general lighting through LEDs.”

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