Microplasticity of silicon crystals

The low-frequency (1 Hz) internal friction (Q^–1) method was used to study the microplasticity of silicon whisker crystals grown by the method of chemical gas-transport reactions in a closed ampoule. A study was made of p-type crystals with the growth axis 111, 1–60 in diameter, working length 1–3 mm, both in the original state and after plastic ( 1%) deformtion by torsion. The temperature and amplitude dependences of Q^–1 were studied in 5·10^–5 torr vacuum. The amplitude of alternating vibrations was within the range 10^–5–10^–3 and the axial stresses were 10⁶–10⁷ N/m². The experimental results led to the conclusion that the microplasticity of undeformed silicon whiskers was due to heterogeneous nucleation of dislocations in stress concentration regions near surface defects, assisted by thermal fluctuations. In deformed whiskers the microplasticity was attributed to the nucleation and motion along dislocations of single and double thermal kinks in accordance with the Seeger model.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 88–93, May, 1980.