Annealing of electron-, proton-, and ion-produced vacancies in Si
- Department of Physics, University of Winnipeg, Winnipeg, Manitoba R3B 2E9 (Canada)
- Departement de Physique, Universite de Montreal, Case Postale 6128 Succ. Centre-Ville, Montreal, Quebec H3C 3J7 (Canada)
- Joint Institute for Nuclear Research, Dubna (Russian Federation)
- Department of Materials Science, Lanzhou University, Lanzhou 730000 (China)
Positron lifetime and Doppler measurements were performed on float-zone-refined and variously doped Czochralski-grown Si. The samples were irradiated by various particles (e{sup -}, p, Kr) with energies between 2 MeV and 245 MeV. Electron or proton irradiation gave rise to divacancies, whereas the damage from ion implantation (Kr) was mainly in the form of four-vacancy clusters, with only a small fraction of vacancies in the form of divacancies. In the case of impurity-lean Si, detailed isothermal annealing at various temperatures between 125 deg. C and 500 deg. C showed that after an initial fast decrease in divacancy concentration, a much slower process of vacancy agglomeration took place. At 450 deg. C agglomeration steadily progressed even after 30 h of annealing at which point the average cluster size corresponded to ten monovacancies. In impurity-rich Si, containing oxygen and dopants, there is nearly no initial decrease in vacancy concentration, and isothermal and isochronal annealings showed that vacancy agglomeration was also nearly absent. Doppler data showed that vacancy-dopant complexes slowly acquired oxygen as annealing progressed, and these complexes survived annealing at 500 deg.C for many hours. Measurements between 8 K and 530 K on samples containing divacancies, or larger clusters, showed a temperature dependence of the positron trapping rate that cannot be explained by the clusters being negatively charged, but can be explained if neutral clusters have a weakly bound positron state which at low temperatures makes trapping more efficient. Generally, the present positron experiments have given an indication for the type of defects that survive annealing at temperatures where electron paramagnetic resonance and infrared spectroscopy yield little useful information.
- OSTI ID:
- 20788005
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 73, Issue 11; Other Information: DOI: 10.1103/PhysRevB.73.115202; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABSORPTION SPECTROSCOPY
ANNEALING
CRYSTALS
DOPED MATERIALS
ELECTRON BEAMS
ELECTRON SPIN RESONANCE
ELECTRONS
INFRARED SPECTRA
ION BEAMS
ION IMPLANTATION
IRRADIATION
MEV RANGE
OXYGEN
PHYSICAL RADIATION EFFECTS
POSITRONS
PROTONS
SEMICONDUCTOR MATERIALS
SILICON
TEMPERATURE DEPENDENCE
TRAPPING
VACANCIES