Comparative Study of Defect Properties in GaN: Ab initio and Empirical Potential Calculations

Conference · Mon Apr 05 04:00:00 EDT 2004

OSTI ID:15007643

Gao, Fei; Bylaska, Eric J; El-Azab, Anter; Weber, William J

Density functional theory (DFT) is used to study the formation, properties and atomic configurations of monovacancies, antisite defects and possible interstitials in GaN. The relaxation around a vacancy is generally small, but the relaxation around antisite defects is large, particularly for a Ga antisite defect, which is not stable and converts to an N-N<0001> split interstitial. All N interstitials, starting from any possible sites, eventually transfer into the N-N split interstitials, forming N molecules. In the case of Ga interstitials, the most favorable configuration is the Ga octahedral interstitial. However, it is found that the Ga-Ga<> split interstitial can bridge the gap between non-bonded Ga atoms along the <11-2> direction, which leads to the formation of Ga atomic wires in GaN, with bond distance close to those noted in bulk Ga. In addition, two representative potentials, namely Stillinger-Weber and Tersoff-Brenner potentials, have been employed to deter mine the formation of defects using molecular dynamics (MD) method in GaN. The MD results are discussed and compared to DFT calculations. The present DFT and MD results provide guidelines for evaluating the quality and fit of empirical potentials for large-scale simulations of ion-solid interaction and thermal annealing of defects in GaN.

• Research Organization: Pacific Northwest National Lab., Richland, WA (US), Environmental Molecular Sciences Laboratory (US)
• Sponsoring Organization: US Department of Energy (US)
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 15007643
• Report Number(s): PNNL-SA-40322; 3443a; 8208; 3448; KC0201020
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANNEALING
DEFECT PROPERTIES
DENSITY FUNCTIONAL METHOD
DENSITY FUNCTIONAL THEORY
ENVIRONMENTAL MOLECULAR SCIENCES LABORATORY
GALLIUM NITRIDE
GALLIUM NITRIDES
INTERSTITIALS
MOLECULAR DYNAMICS
MOLECULAR DYNAMICS METHOD
RADIATION EFFECTS
VACANCIES