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Growth of heavily tin-doped Si
|Ichiro Yonenaga 1, Toshinori Taishi 2, Kaihei Inoue 1, Kentaro Kutsukake 1, Yuki Tokumoto 1, Yutaka Ohno 1|
1. Institute for Materials Research, Tohoku University, 2-1-1, Katahira, Aoba-ku, Sendai 980-8577, Japan
Recently doping of isovalent substitutional impurities (Group-IV) into semiconductors have been attracted keen interests. Such impurities have almost no effects electrically but have unique interactions with harmful defects to improve the device yield and output through the local strain compensation. Particularly, Ge is effective to suppress formation of vacancy-oxygen clusters in electron-irradiated Si crystals . In comparison with Ge, information on Sn is rather limited except some studies for lack of suitable crystals. These isovalent impurities are expected to affect local vibration of interstitially dissolved Oi and substitutional Cs in Si as known in SiGe alloys . Here, we report the Czochralski-growth of Si crystals heavily doped with Sn and to discuss compositional variation along the growth direction of the crystals. Also, doping effects on infrared absorption spectra of Oi and Cs due to the dopant-induced elastic strain are shown.
Si single crystals heavily doped with Sn were grown by the Czochralski method with a constant pulling rate in a flowing Ar gas atmosphere. Certain amount of high purity Sn pellets was added as a dopant. - or -oriented Si seeds were used.
A full single crystal, as large as around 20 mm in diameter and 40 mm in length, was obtained under a pulling rate of 8 mm/h. The Sn concentration at the top part of the crystal was 1.5 x 1019 cm-3, determined by ICP-OES and WDX, then increased along the growth direction, and reached to 4 x 1019 cm-3, close to the solubility limit in a literature . The variation of the Sn concentration well followed to a normal segregation with a coefficient 0.016 . From the optical absorption peak at 1106 cm-1 of Oimeasured by FT-IR, the Oi concentrations in the crystals were around 8 x 1017 cm-3. The absorption peak shifted to the low wave number side with an increase in [Sn] along the growth direction, possibly due to the expansion of Si–Si bonds.
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 I. Yonenaga et al., Physica B 308-310, 539 (2001).
 F. A. Trumbore, Bell Syst. Techn. J. 39, 205 (1960).
Presentation: Oral at 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17, Topical Session 5, by Toshinori Taishi
See On-line Journal of 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17
Submitted: 2013-04-03 04:33 Revised: 2013-07-03 18:55