Orientation Control of Bulk GaN Substrates Grown via Hydride Vapor Phase Epitaxy

P.R. Daniels*, E.A Preble, T. Paskova, and D. Hanser

Kyma Technologies, Inc. 8829 Midway West Road, Raleigh, NC 27617 *Email: daniels@kymatech.com Phone: (919) 789-8880

Keywords: GaN, substrate orientation, HVPE, crystal growth

ABSTRACT

The growth of GaN bulk crystals via the HVPE process and the manufacturing of orientation controlled substrates from the GaN crystals are presented. An HVPE process has been produced for growth of bulk GaN on sapphire with an AlN interfacial seed layer. This process has allowed for the production of GaN substrates up to 2 inches in diameter. Due to the stress associated with the growth of GaN on sapphire, orientation control can be problematic. However, a method for orientation control has been implemented that employs XRD for identification of the material orientation and a lapping procedure for correction. Using this method, substrate orientation can be controlled to within ±0.25 degrees of the desired off cut. After the substrates undergo orientation correction, a polishing process is used that employs both mechanical polishing and chemical mechanical polishing. The final polish has been shown to produce surfaces with roughness values less than 1 nm which is suitable for epitaxial growth.

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