Electrically active defect annealing in neutron and in ion-damaged Si

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Abstract
Hall effect and electrical conductivity measurements of defect annealing in 1 ohm-cm n-type and 2 ohm-cm p-type silicon were made following neutron irradiation at ∼50°C. Measurements were also made following 400-keV B11 ion implantation into a 100 ohm-cm n-type Si substrate. As the neutron fluence is increased the electrical effects of the damage eventually outweigh those of the chemical dopants, and further changes in the electrical properties become small. Conversely, significant electrical recovery upon annealing begins only when the electrical effects of the remaining damage become comparable to those of the chemical dopants. This condition will occur at higher anneal temperatures for higher fluence irradiations. The neutron fluence dependence of the damage and the annealing is interpreted in terms of the neutron energy per cm3. E, spent in atomic processes divided by the number/cm3, N, of electrically active dopants. When E/N ≤ 0.5 keV the electrical measurements show that the predominant defect annealing occurs below 400°C. However, when E/N > 0.5 keV electrical measurements emphasize the annealing at temperatures > 400°C. After 500°C annealing, energy levels in neutron damaged Si are observed at Ev +0.1 and Ev +0.15 eV in p-type and at Ec -0.33 eV in n-type Si. Application of the E/N criteria to room temperature implant-doped Si predicts that the electrical effects will be dominated by lattice damage even if all the implanted ions are substitutional.