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SDK to Produce High-Power Blue LED Chips

October 25, 2004

Showa Denko K.K. (SDK) has developed a blue light-emitting diode (LED) based on gallium nitride (GaN) having brightness at the highest level on the market. SDK will start marketing the product next year for such growing applications as mobile phones, outdoor displays, illumination and automotive devices.

The new 12 mW LED with a flip chip structure1) has been developed by combining SDK’s proprietary technologies for the production of compound semiconductors and hard disk media. Compared with the existing products on the market, the newly developed LED has additional advantages of low forward voltage and low electricity consumption.

Thus, the new product is expected to be used in backlighting of liquid crystal displays (LCDs) and in photoflash units of mobile phones. Furthermore, as the unique flip chip structure provides better heat dissipation and higher reliability, the new product will find applications in automotive devices and general illumination.

SDK is now constructing a plant in Chiba to produce 30 million units a month of GaN-based blue LED chips. Sample shipment will begin in November this year. Commercial production will start next year, and the company plans to sell 30 million units per month by year-end. SDK is planning to expand the production capacity to meet a growing demand and to increase the annual sales to ¥20 billion in 2008.

GaN LED chips, which emit near ultraviolet to green light at wavelengths of 360-530 nm, are now used mainly in backlighting for LCDs and keypad light source for mobile phones.

Blue LEDs can be combined with fluorescent materials to provide white lighting. With the improvement in power, demand for blue LEDs will increase rapidly for use in car headlights and general illumination. Furthermore, blue LEDs can be combined with GaN green LEDs and aluminum indium gallium phosphide (AlInGaP) red LEDs for use in color displays and backlighting of LCD TV screens. It is therefore predicted that the market for GaN LEDs will continue to grow at an annual rate of 20% or more.

Since early 1970s, SDK has been in the optoelectronic materials business, producing epitaxial wafers and chips of gallium phosphide (GaP) and other types of compound semiconductors. Except for GaN, SDK has the largest share in the world market of compound semiconductors for optoelectronic devices. SDK is expanding the business by providing epitaxial wafers for laser diodes used in DVD/CD optical pickups2) as well as developing AlInGaP LEDs and GaN LEDs, both with exceptional brightness.

In the ongoing medium-term consolidated business plan called the “Sprout Project,” SDK classifies the compound semiconductor operation as one of the “strategic growth businesses,” allocating a substantial portion of its resources into the operation.

For further information, contact:

Marketing Dept., Electronic Materials Div. (Phone: 81-3-5470-3293)


1. SDK’s compound semiconductor portfolio

  • 1)LED materials (epitaxial wafers and chips):
    GaP (yellow-green)
    GaAs (infrared), AlGaAs (red, infrared)
    AlInGaP (red to yellow-green)
  • 2) Epitaxial wafers for optical pickups:
    AlInGaP (red) for DVDs
    AlGaAs (infrared) for CDs
  • 3)Single crystal mirror wafers and epitaxial wafers for optical fiber communications: InP
  • 4)Epitaxial wafers for high-frequency communications: InP, GaAs

2. Terminology

1) Flip chip structure

  • A structure of LED chips in which anodes and cathodes are on the epitaxial layer, and the chips are assembled after being turned upside down. (Fig.1.)
  • Compared with the conventional face-up type (Fig. 2) that uses wire for bonding and emits light from the top, our LED with the flip chip structure has a transparent substrate so that light can be brought out from all parts of the chip.
  • The efficiency can be increased further by adding an appropriate reflector to the epitaxial layer side.
  • The device can be miniaturized because the electrode side (lower part) can be directly assembled by the use of gold bumps or solder.
  • Due to improvement in heat dissipation and reliability, demand for LEDs with the flip chip structure is expected to grow for automotive and illumination applications.

2) Laser diodes for optical pickups

  • Laser diodes used for reading out information recorded on CD and DVD. Similar to the needle for analog-type records.
  • For both CD and DVD, there are two different types of optical pickups: read only and read/write. Diodes with higher laser power are used for the latter application.
Fig. 1 Flip Chip Structure      Fig. 2 Face-up Type