Seren Photonics has developed a process to manufacture semi-polar (11-22) and non-polar (11-20) GaN templates with significantly reduced defect density (compared to other template methods). Furthermore, GaN thickness on the template is typically 5µm, thus greatly reducing wafer bow due to thermal mismatch with the underlying sapphire.
Semi-polar and non-polar GaN materials have been shown to overcome two of the LED industry's main problems, namely:
To date however, such materials have only been available in small pieces and small quantities owing to the method of manufacture. Until now, semi-polar and non-polar GaN had to be cut from a GaN bulk crystal that had been grown by the HVPE or the ammonothermal method. This approach yields only small pieces, of the order of 10-15mm square. Although useful for research and development, the lack of industry standard wafer sizes, e.g. minimum 2", has meant that semi-polar and non-polar GaN has not been seen as commercially viable. Until now that is!
Seren's approach is to create full wafer templates of semi-polar and non-polar GaN. The GaN is grown directly onto a sapphire substrate (hetero-epitaxy) and by using our patented technology, we are able to significantly improve the quality of the material to levels previously unachievable from the hetero-epitaxy approach.
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