Hydrogen configurations, formation energies, and migration barriers in GaN

• Published in: Journal of applied physics 2003-08, Vol.94 (4), p.2311-2318
• Main Authors: Wright, A. F., Seager, C. H., Myers, S. M., Koleske, D. D., Allerman, A. A.
• Format: Article
• Language: English
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.1592607

Hydrogen configurations, formation energies, and migration barriers in GaN have been obtained from density-functional theory (DFT) calculations employing the generalized-gradient approximation (GGA) for exchange and correlation. The H configurations and formation energies are similar to previous DFT results obtained using the local-density approximation (LDA) for exchange and correlation with the most notable differences being higher formation energies for H0 (0.2 eV) and H2 (0.1 eV) in the GGA calculations and a preference for H+ at a bond-centered site. GGA H migration barriers differ from LDA values with the largest differences being 0.4 eV higher GGA H+ migration barriers. Refined measurements of field-induced H+ drift in GaN p/n+ diodes have also been performed. Modeling of these results indicates that the sum of the H+ diffusion activation energy and the H+ binding energy to ionized Mg acceptors is 1.76 eV. The corresponding GGA result (1.6 eV) is in good agreement with the measured value.