Surface lifetimes of Ga and growth behavior on GaN (0001) surfaces during molecular beam epitaxy

We report a study of the desorption behavior of Ga on the GaN(0001) surface and the growth behavior of GaN during molecular beam epitaxy. A desorption activation energy of 2.2±0.2 eV is measured for Ga adatoms. Porous columnar features in the GaN microstructure are observed that are enhanced by higher growth temperatures and eliminated by growing Mg or Si doped GaN. We propose a model for this observation.