Thought for the month
“You cannot have freedom without a rule of law ... and if you don't have it, what you tend to get is corruption and that is death to freedom, it's death to truth, it's death to honour, it's death to democracy.”
Margaret Thatcher, 1 October 1996.
Thursday, 10 February 2011
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.