Aonex and Kyma develop improved GaN growth substrates

Joint development work hopes to yield large-area GaN wafers for improved growth of devices including LEDs.

Aonex, a subsidiary of Arrowhead Research Corporation, will provide Kyma with access to its proprietary wafer technology, A-Sapph™. Kyma will work to leverage the superior properties of A-Sapph to produce large-area wafers suitable for the manufacture of GaN devices.

Aonex and Kyma believe that large-area wafers could dramatically reduce the cost of GaN devices by enabling an increase in the number of chips per wafer while also substantially improving yields.

Keith Evans, Kyma's president and CEO, said: "The combined attributes of Aonex’s A-Sapph substrate technology and Kyma's proprietary high-growth-rate, low defect density GaN crystal growth technology have great potential to reduce the costs of a broad range of high performance nitride semiconductor devices."

Evans told LEDs Magazine that after the initial collaborative investigation there are several different potential routes to market. "Certainly there is potential to offer both c-plane and non-polar Kyma GaN on Aonex sapphire-on-poly-AlN. But there are other possibilities also in the area of bulk GaN growth, which we are not saying much about publicly."

A-Sapph substrates are comprised of an ultra-thin layer of single crystal sapphire (<500 nm) that is bonded to a polycrystalline aluminum nitride (AlN) support substrate. The resulting substrate has a coefficient of thermal expansion (CTE) that is nearly identical to GaN yet offers an industry-standard sapphire growth surface (both c- and r-plane) suitable for MOCVD and HVPE growth environments.

A-Sapph substrates also offer substantially higher thermal conductivity than bulk sapphire, and this can result in significantly improved growth uniformity. Taken together, these improved thermal characteristics could enable the scaling of GaN production to larger wafer diameters and corresponding lower costs.

Aonex has also designed A-Sapph substrates to enable vertical LED fabrication without laser lift-off, which is often used to remove the sapphire growth substrate.

Kyma Technologies develops GaN substrate materials for a broad range of nitride semiconductor device applications. Most current nitride semiconductor devices are fabricated from foreign substrates such as sapphire and silicon carbide, and GaN substrates have the potential to enable important improvements in device performance, reliability, and cost.

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