Thought for the month

“History isn’t just the story of bad people doing bad things. It’s quite as much a story of people trying to do good things. But somehow something goes wrong.” C.S. Lewis, Author (1898 – 1963).

Thursday, 10 February 2011

Avoiding defects

Recent work from North Carolina State University describes a technique for reducing defects in gallium nitride (GaN) epitaxial films grown on sapphire substrates (‘Embedded voids approach for low defect density in epitaxial GaN films’, Appl. Phys. Lett. 98, 023115 (2011), 17 January and this link). By embedding a series of high density micro-voids within thin films, the group were able to create sinks or termination sites for dislocations. According to the team, TEM and AFM analysis confirm dislocation density reductions of 2-3 orders of magnitude with particular benefits for LEDs emitting in the ultraviolet range.

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