Threshold displacement energy in GaN: Ab initio molecular dynamics study

Large-scale ab initio molecular dynamics method has been used to determine the threshold displacement energies E-d along five specific directions and to determine the defect configurations created during low energy events. The E-d shows a significant dependence on direction. The minimum E-d is determined to be 39 eV along the <(1) over bar 010 > direction for a gallium atom and 17.0 eV along the <(1) over bar 010 > direction for a nitrogen atom, which are in reasonable agreement with the experimental measurements. The average E-d values determined are 73.2 and 32.4 eV for gallium and nitrogen atoms, respectively. The N defects created at low energy events along different crystallographic directions have a similar configuration (a N-N dumbbell configuration), but various configurations for Ga defects are formed in GaN. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3153277]