Introduction and recovery of point defects in electron-irradiated ZnO

Journal Article · Mon Aug 15 00:00:00 EDT 2005 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PhysRevB.72.085206· OSTI ID:20719352

Tuomisto, F; Saarinen, K; Look, D C; Farlow, G C ^[1]

---

1. Laboratory of Physics, Helsinki University of Technology, P.O. Box 1100, 02015 TKK (Finland)

We have used positron annihilation spectroscopy to study the introduction and recovery of point defects in electron-irradiated n-type ZnO. The irradiation (E{sub el}=2 MeV, fluence 6x10{sup 17}cm{sup -2}) was performed at room temperature, and isochronal annealings were performed from 300 to 600 K. In addition, monochromatic illumination of the samples during low-temperature positron measurements was used in identification of the defects. We distinguish two kinds of vacancy defects: the Zn and O vacancies, which are either isolated or belong to defect complexes. In addition, we observe negative-ion-type defects, which are attributed to O interstitials or O antisites. The Zn vacancies and negative ions act as compensating centers and are introduced at a concentration [V{sub Zn}]{approx_equal}c{sub ion}{approx_equal}2x10{sup 16}cm{sup -3}. The O vacancies are introduced at a 10-times-larger concentration [V{sub O}]{approx_equal}3x10{sup 17}cm{sup -3} and are suggested to be isolated. The O vacancies are observed as neutral at low temperatures, and an ionization energy of 100 meV could be fitted with the help of temperature-dependent Hall data, thus indicating their deep donor character. The irradiation-induced defects fully recover after the annealing at 600 K, in good agreement with electrical measurements. The Zn vacancies recover in two separate stages, indicating that the Zn vacancies are parts of two different defect complexes. The O vacancies anneal simultaneously with the Zn vacancies at the later stage, with an activation energy of E{sub V,O}{sup m}=1.8{+-}0.1 eV. The negative ions anneal out between the two annealing stages of the vacancies.

• OSTI ID: 20719352
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Vol. 72, Issue 8; Other Information: DOI: 10.1103/PhysRevB.72.085206; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ACTIVATION ENERGY
ANIONS
ANNEALING
ANNIHILATION
CRYSTALS
ELECTRON BEAMS
ELECTRONS
INTERSTITIALS
IONIZATION
IRRADIATION
MEV RANGE
MONOCHROMATIC RADIATION
POSITRONS
SEMICONDUCTOR MATERIALS
SPECTROSCOPY
TEMPERATURE DEPENDENCE
VACANCIES
ZINC OXIDES