Seren introduces LED grade semi-polar GaN templates
Seren Photonics Ltd, a venture-funded spin-out from the UK's University of Sheffield, has announced the launch of its next generation of semi-polar GaN on sapphire templates.
The 11-22 GaN templates continues to be based on Seren's patented approach developed by Tao Wang's team at the University of Sheffield. The improved performance comes through a manufacturing upgrade that not only improves crystal quality, but also enhances manufacturing yield.
This approach has already completed qualification for 2in diameter product and as part of its development activity, Seren has now adapted the enhanced approach to the development of 4in and 6in templates. Customer sampling of 4in templates is expected during Q3 2015, with 6in planned to come online during H1 2016.
"With demand for 4in and 6in accounting for over 75 percent of the sapphire market for LEDs, the need to provide customers with industry standard 4in diameter wafers along with the option to upgrade to 6in makes total commercial sense" said Bedwyr Humphreys chief development officer at Seren Photonics.
A template is a composite or engineered substrate, where one or more layers are added to the original susbstrate. Seren Photonics grows semi-polar GaN (11-22) on m-plane sapphire and non-polar GaN (11-20) on r-plane sapphire.
In the case of semi-polar GaN, the advantage of the template approach is that cost is significantly reduced when compared to bulk GaN and more importantly, templates can be grown on 2, 4 and 6in sapphire. Semi-polar bulk GaN is still only available in small pieces.
Experts in the semi-polar GaN field will know that semi-polar GaN displays anisotropic behaviour under x-ray diffraction. What this means is that, unlike c-plane GaN, semi-polar GaN crystal quality is dependent on the direction along the wafer that the measurement is taken.
This latest development from Seren has overcome this issue yielding a semi-polar GaN layer with isotropic crystal quality. This not only enhances the optical isotropy of the material but also ensures electrical properties such as mobility are also isotropic.
This latest generation is available for sampling in 2in diameter or custom sizes. At less than 5um thick, the GaN layer for these semi-polar templates is the thinnest available on the market today, ensuring minimal wafer bow with maximum defect blocking.