GaN-on-Silicon LED die provide efficient blue-to-white light phosphor drive

August 06, 2015 // By Graham Prophet
Plessey has introduced MaGIC LED dice, manufactured on the company's GaN-on-Silicon technology; these blue emitters, sometimes referred to as blue pump for their ability to pump phosphor to a white colour range, are high brightness LED dice designed for a wide range of medium-to-high power applications including general lighting, signage, commercial, residential and street lighting.

Plessey CTO, Dr. Keith Strickland, said, "Our GaN-on-Silicon technology works particularly well in higher power applications such as high bay, street lights, projector lamps, spot lamps and floodlighting. This current process technology will become the base for our application specific LEDs, the ASLED, which bridges the gap between LED component suppliers, solid state lighting fixture designers and the OEMs."

The manufacturing process produces a vertical LED structure which has the anode as bottom contact and the cathode formed in the top metal layer. The layout of the top metal layer is optimised for a particular LED size and die operating current, and includes one or more bond pads for connecting to the cathode.

Plessey offers its range of blue dice in various wavelength options. Capable of generating over 60% light output efficiency, sometimes referred to as wall plug efficiency (WPE), the dice are supplied to a standard thickness of 150 μm, whilst other thicknesses can be supplied, down to a minimum of 75 μm.

The dice are supplied on a blue tape in single intensity and colour bins to provide close uniformity, and are intended to be used with standard pick and place machines. Samples are available in a variety of die pack formats with blue die wavelengths ranging from 420 nm to 480 nm and from mW to 10W with the PExS4500 range having a typical optical output power of 4000 mW from a 3A drive current.

Plessey adds, "We are seeing a definite move away from discrete PLCC designs, especially in the higher power applications. By having our own growth and semiconductor processing facility in Plymouth, Plessey provides the flexibility and speed of response required for a vast range of high-end applications that can use the thermal and light output from our silicon LED die."