Observation of vacancy in crystalline silicon using low-temperature ultrasonic measurements

Terutaka Goto, Hiroshi Yamada-Kaneta, Koji Sato, Masatoshi Hikin, Yuichi Nemoto, Shintaro Nakamura

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


We have successfully observed isolated vacancies in crystalline silicon using low-temperature ultrasonic measurements. The floating zone (FZ) silicon exhibits softening in longitudinal elastic constants consisting of transverse C44 and (C11 - C12)/2 in part with decreasing temperature below 20 K down to 20 mK. The applied magnetic fields of up to 16 T at the base temperature 20 mK show no effect on the low-temperature softening in non-doped FZ silicon, while the fields of up to 2 T suppress the low-temperature softening in boron-doped FZ silicon. This experiment suggests that isolated vacancies with non-magnetic charge state V0 in the non-doped FZ silicon and with magnetic charge state V+ in the boron-doped FZ silicon lead to the low-temperature softening. We have also observed the low-temperature softening in the Pv-region of non-doped Czochralski (CZ) silicon ingot, which indicates vacancy distribution. A coupling of electric quadrupoles of triplet state of vacancy orbital to the elastic strains of the sound waves is discussed for description of the low-temperature softening.

Original languageEnglish
Pages (from-to)109-114
Number of pages6
JournalPhysica B: Condensed Matter
Publication statusPublished - 2007 Dec 15


  • Electric quadrupole
  • Silicon
  • Softening
  • Ultrasound
  • Vacancy

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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