Neutral nitrogen acceptors in ZnO: The {sup 67}Zn hyperfine interactions

• Published in: Journal of applied physics 2014-03, Vol.115 (10)
• Main Authors: Golden, E. M., Giles, N. C., Evans, S. M., Halliburton, L. E.
• Format: Article
• Language: English
• Subjects: CATIONS; CHARGE STATES; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CRYSTAL STRUCTURE; CRYSTALS; ELECTRON SPIN RESONANCE; HYPERFINE STRUCTURE; N-TYPE CONDUCTORS; NITROGEN; NITROGEN 14; OXYGEN IONS; PARAMAGNETISM; VAPORS; ZINC 67; ZINC IONS; ZINC OXIDES
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.4867736

Electron paramagnetic resonance (EPR) is used to characterize the {sup 67}Zn hyperfine interactions associated with neutral nitrogen acceptors in zinc oxide. Data are obtained from an n-type bulk crystal grown by the seeded chemical vapor transport method. Singly ionized nitrogen acceptors (N{sup −}) initially present in the crystal are converted to their paramagnetic neutral charge state (N{sup 0}) during exposure at low temperature to 442 or 633 nm laser light. The EPR signals from these N{sup 0} acceptors are best observed near 5 K. Nitrogen substitutes for oxygen ions and has four nearest-neighbor cations. The zinc ion along the [0001] direction is referred to as an axial neighbor and the three equivalent zinc ions in the basal plane are referred to as nonaxial neighbors. For axial neighbors, the {sup 67}Zn hyperfine parameters are A{sub ‖} = 37.0 MHz and A{sub ⊥} = 8.4 MHz with the unique direction being [0001]. For nonaxial neighbors, the {sup 67}Zn parameters are A{sub 1} = 14.5 MHz, A{sub 2} = 18.3 MHz, and A{sub 3} = 20.5 MHz with A{sub 3} along a [101{sup ¯}0] direction (i.e., in the basal plane toward the nitrogen) and A{sub 2} along the [0001] direction. These {sup 67}Zn results and the related {sup 14}N hyperfine parameters provide information about the distribution of unpaired spin density at substitutional neutral nitrogen acceptors in ZnO.