Direct observation of vacancy in silicon using sub-Kelvin ultrasonic measurements

• Published in: Materials science & engineering. B, Solid-state materials for advanced technology Vol. 134; no. 2; pp. 233 - 239
• Main Authors: Goto, Terutaka, Yamada-Kaneta, Hiroshi, Saito, Yasuhiro, Nemoto, Yuichi, Sato, Koji, Kakimoto, Koichi, Nakamura, Shintaro
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 25.10.2006
• Subjects: Charge states; Silicon; Softening; Ultrasound; Vacancy; Charge states; Silicon; Softening; Vacancy; Ultrasound
• ISSN: 0921-5107; 1873-4944
• DOI: 10.1016/j.mseb.2006.07.038

We carried out sub-Kelvin ultrasonic measurements for observation of vacancies in crystalline silicon. The longitudinal elastic constants of non-doped and B-doped floating zone (FZ) silicon crystals in commercial base revealed low-temperature elastic softening below 20 K. The applied magnetic fields turns the softening of the B-doped FZ silicon to a temperature-independent behavior, while the fields up to 16 T at base temperature 20 mK make no effect on the softening of the non-doped FZ silicon. This result means that the vacancy accompanying the non-magnetic charge state V 0 in the non-doped silicon and the magnetic V + in the B-doped silicon is responsible for the low-temperature softening through the Jahn–Teller effect. The direct observation of the vacancy using the sub-Kelvin ultrasonic measurements advances point defects controlling in silicon wafers and semiconductor devices.