Cascade phonon-assisted trapping of positrons by divacancies in n-FZ-Si(P) single crystals irradiated with 15 MeV protons

• Main Authors: Yu, Arutyunov N, Emtsev, V V, Krause-Rehberg, R, Kessler, C, Elsayed, M, Oganesyan, G A, Kozlovski, V V
• Format: Conference Proceeding
• Language: English
• Subjects: ANNEALING; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CROSS SECTIONS; Crystal defects; Divacancies; DOPED MATERIALS; HALL EFFECT; IRRADIATION; MONOCRYSTALS; PHONONS; Positron lifetime spectroscopy; POSITRONS; PROTONS; Radiation damage; Single crystals; SPECTROSCOPY; Temperature dependence; Trapping
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/1.4865601

The trapping of positrons by the radiation defects in moderately doped oxygen-lean n-FZ-Si(P) single crystal irradiated with 15 MeV protons has been investigated in a comparative way using the positron lifetime spectroscopy and Hall effect measurements. The experiments were carried out within a wide temperature interval ranging from 25 K – 29 K to 300 K. The positron trapping rate for divacancies was reconstructed in the course of many-stage isochronal annealing. The concentration and the charged states of divacancies (V2− and V2−−) were estimated. The temperature dependency of the trapping cross section of positrons by the negatively charged divacancies is in a good agreement with the data of calculations based on the assumptions of the cascade phonon-assisted mechanism of exchange of the energy between the positron and acoustic long-wave phonons. Obeying ∼ T−3 law, the cross-section of the trapping of positrons by divacancies changes considerably ranging from ∼1.7×10−12 cm2 (66 – 100 K) to ∼2×10−14 cm2 (≈ 250 K). The characteristic length of trapping of the positron by V2−− divacancy was estimated to be l0(V2−−)≈(3.4±0.2)×10−8 cm.