Photoelectrochemical Etching for Chip Shaping Of LEDs
Tech ID: 23784 / UC Case 2009-157-0
A novel process to chip shape LEDs though photochemical (PEC) etching.
Light emitting diodes’ (LEDs) external quantum efficiency is limited by light emitted into guided modes being trapped in the material. When wafers are diced, the resulting sidewalls are smooth and vertical resulting in most of the light reflecting back into the material where it is eventually lost. To counteract this phenomenon, shaping is done to modify the geometry to form non rectilinear designs, which decrease the amount of trapped light. This chip shaping involves shaping the material and substrate which may have different compositions. Moreover, the shaping is typically accomplished through crystallographic wet or dry etching or by device sawing using specialty blades.
Researchers at the University of California, Santa Barbara have developed a novel process to chip shape LEDs though photochemical (PEC) etching. This process can directly etch the material in between LEDs that are grown on III-V substrates. By varying the angle of the incident light during PEC etching, the angle of the resulting sidewalls can be controlled to create sloped sidewalls. These walls can then scatter guided modes out of the material rather than reflecting them back, to increase the external quantum efficiency.
- Increased external quantum efficiency
- Low cost etching
- Rapid etching
- Eliminate the need of mechanical etching
- Possible automation of the etching process
- LED shaping
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