Surface reconstructions occurring on the (0001) surface of wurtzite GaN are studied using scanning tunneling microscopy, electron diffraction, and Auger electron spectroscopy. The family of reconstructions found on this face includes 2×2, 5×5, 6×4, and “1×1”, in order of increasing surface Ga/ N ratio. Detailed experimental results are presented for each of these reconstructions. First-principl...