Office of Technology Transfer – University of Michigan

Wafer Recycling for Fabrication of Thin-Film Inorganic LEDs

Technology #6023

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Researchers
Stephen R. Forrest
Managed By
Joohee Kim
Licensing Specialist, Physical Sciences & Engineering 734.764.8202
Patent Protection
US Patent Pending
US Patent Pending

Researchers at the University of Michigan have developed a technique for the fabrication of low cost, thin-film, inorganic light emitting diodes (LEDs) that allows for the indefinite reuse and recycling of wafers. Compound semiconductors, such as those used in inorganic LEDs, are the basis for many of the highest performance optical and electronic devices in use today. However, their widespread commercial application has been limited due to high substrate cost. Device costs can be significantly reduced if the substrate can be reused in a simple, fully non-destructive, and rapid process.

Design Details

The method for fabricating inorganic LEDs developed at the University of Michigan allows for the indefinite reuse and recycling of wafers and is based on non-destructive epitaxial lift-off (ND-ELO). The method employs a combination of epitaxial “protection layers”, plasma cleaning techniques to return the wafers to their original, pristine and epi-ready condition following epitaxial layer removal, and adhesive-free bonding to a secondary plastic substrate. The proposed technology also includes a method for fabricating three-color LED pixel arrays using blue/green/red inorganic LED pixels and by combining blue or ultraviolet inorganic LEDs with inorganic phosphors for down conversion. The technology also supports scaling up the display size using a stretchable substrate. Using the proposed technology, inorganic LEDs can be employed in light-weight, semitransparent, stretchable, conformal or flexible display platforms.

Applications

  • High-performance LED lighting

Advantages

  • Eco-friendly
  • Low cost
  • Support for light-weight, semi-transparent, stretchable, conformal or flexible display platforms