Scanning electron microscopy studies of GaN

The surface of vapor−deposited GaN and the cross section of GaN light−emitting diodes were examined using secondary electron emission, cathodoluminescence, beam−induced conductivity, and beam−induced voltage. The GaN layer is an assemblage of identically oriented microcrystals. The Zn distribution in the insulating layer is usually not uniform. High built−in fields occur at the two edges of the insulating layer.