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Energetics of H and NH2 on GaN(1010)


We present first-principles calculations of the formation energy for H-terminated GaN(101¯0) surfaces. The calculations indicate that H adsorption on GaN(101¯0) will proceed by saturation of pairs of Ga and N dangling bonds rather than through exclusive occupation of only one type of bonding site. At T=0, the surface energy of the fully H-terminated surface is found to be 0.02 eV/cell, compared to 1.95 eV/cell for the bare surface. We present results for the N-H and Ga-H stretching and bending eigenfrequencies. Dissociative adsorption of NH3 via the formation of N-H and Ga-NH2 bonds is exothermic and reduces the surface formation energy to a value which is less than 0.1 eV at T=0. The implications of these results for the origin of nanopipe defects in GaN are examined.


Northrup, J. E. ; Di Felice, R. D. ; Neugebauer, J. Energetics of H and NH2 on GaN(1010). Physical Review B. 1997 August 15; 56 (8): R4325-8.