Formation of nanovoids in high-dose hydrogen implanted GaN

The formation of nanovoids upon high-dose hydrogen implantation and subsequent annealing in GaN is investigated by transmission electron microscopy. The epitaxial GaN layers on sapphire were implanted at room temperature with H-2(+) ions at 100 keV with a dose of 13x10(16) cm(-2). Cross section transmission electron microscopy investigations revealed that nanovoids about 2 nm in diameter had formed during hydrogen implantation at room temperature while large microcracks (similar to 150-200 nm long) occurred upon annealing (1 h at 700 degrees C) leading to surface blistering. The nanovoids serve as precursors to the microcrack formation and are essential for the blistering process. (c) 2006 American Institute of Physics.