Relaxation process of ion irradiation defects in IV-semiconductors

Relaxation process of ion irradiation defects in IV-semiconductors (Si, Si0.85Ge0.15, Ge, and heavily P-doped (∼1020 cm−3) n+-Si) was investigated. The IV-semiconductors were irradiated with 25 keV Ar+ ions (dose: 1×1013–1×1016 cm−2, dose rate: 3×1011–6×1012 cm−2 s−1, temperature: 25–250 °C). Amorphicity was comprehensively evaluated by using spectroscopic ellipsometry. For samples irradiated at temperatures around 100 °C, dose rate dependence of amorphicity was remarkably observed. The Arrhenius plot of critical dose rate, at which defect generation and annihilation rates were balanced, showed that activation energies for defect relaxation process were 0.43, 0.51, 0.88, and 0.18 eV for Si, Si0.85Ge0.15, Ge, and n+-Si, respectively. These results suggest that defect relaxation process is governed by migration of V0 in Si, Si0.85Ge0.15, and Ge, while V2− in n+-Si. The migration energy of V0 in Si0.85Ge0.15 obeys the Vegardʹs law.