The Influence of Crystal Structure on the Lattice Sites and Formation Energies of Hydrogen in Wurtzite and Zinc-Blende GaN
- Sandia National Laboratories
Charge-state calculations based on density-functional theory are used to study the formation energy of hydrogen in wurtzite and zinc-blende GaN as a function of Fermi level Comparison of these results reveals notable differences including a 0.56 eV lower formation energy for H2 in wurtzite, and different configurations for H2 and H- in the two crystal structures. Furthermore, H+ is found to be equally stable at bond-centered and anti-bonding sites in wurtzite, whereas it is unstable at a bond-centered site in zinc blende. These differences are due to distinct features of the two crystal structures including: the lower symmetry of wurtzite which provides a wider selection of bonding sites for H+, and the existence of extended three-fold symmetric channels oriented along the c-axis in wurtzite which provide more favorable bonding configurations for H2 and H-.N-H+ stretch-mode vibration frequencies, clustering of ?3+ in p-type material, and diffusion barriers for H" are also investigated in wurtzite GaN. A diffusion barrier of 1.6 eV is found for H- in wurtzite GaN, significantly lower than a previous estimate, and a tendency for H+ clustering in p-type material is found.
- Research Organization:
- Sandia National Laboratories, Albuquerque, NM, and Livermore, CA
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 3338
- Report Number(s):
- SAND99-0281J; ON: DE00003338
- Journal Information:
- Physical Review B, Journal Name: Physical Review B
- Country of Publication:
- United States
- Language:
- English
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