Solid State Lighting (LEDs) using Translucent vGaN™ technology

Today, virtually all of the commercially available LEDs produced using nitride semiconductors use sapphire as the starting substrate. This is becoming expensive and there are both technical challenges and cost penalties to increase the size of the wafer. Increasingly, the lighting industry is looking to adopt a silicon substrate solution. However, unlike sapphire wafers which are transparent, one of the key problems associated with using silicon is that silicon absorbs visible light and consequently LEDs produced on silicon automatically loose approximately half of their light output (LEDs emit in a lambertian pattern, i.e. equally in all directions).

Translucent has solved this issue very simply using a very high quality mirror called a Distributed Bragg Reflector (DBR). This is a lattice matched stack of materials all grown sequentially at Translucent with high and low refractive index. This patented mirror technology derived from the baseline cSOI™ technology is called Mirrored-Si™. The substrates with Mirrored-Si™ are designed using single crystal superlattices of REO and silicon, which because of the large refractive indices between the two materials, produce very efficient mirrors with peak reflectivities >90% at 500nm while delivering stop bands in excess of 100nm. Typical uniformities for these parameters are ~1%.

The rare earth oxide material developed by Translucent is the first material that is both single crystal and compatible with silicon and subsequent nitride epitaxy, from which a mirror like structure can be constructed. The vGaN™ process is then used to transform the Mirrored-Si™ substrates into device-ready template wafers for LED epitaxy growth. The Mirrored Si™ layers make the silicon surface highly reflective at typical LED emission wavelengths and eliminate the substrate loss.

Translucent News

  • 16-Feb-12 This year's Prism Awards videos are live on the Prism Awards Website.
  • 15-Feb-12 Michael Lebby to speak at SVC's Executive Forum, 12:30pm, 1-May-12, Santa Clara Convention Center.
  • 26-Jan-12 Michael Lebby presented the award for Green Photonics at the Prism Awards Ceremony.
  • 03-Jan-12 Translucent is referenced in an article in the current issue of Semiconductor Today Magazine.
  • 20-Dec-11 Translucent's Michael Lebby gave an invited talk at Honet 2011.
  • 30-Nov-11 Article about Translucent's technology is published in Oct/Nov issue of Semiconductor Today.
  • 12-Oct-11 Translucent visits PIDA in Taiwan.