2003 Fiscal Year Final Research Report Summary
Growth and Fundamental Properties of GeSi Bulk Crystals
| Project/Area Number |
13450001
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied materials science/Crystal engineering
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| Research Institution | Tohoku University |
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Principal Investigator |
YONENAGA Ichiro Tohoku University, Institute for Materials Research, Associate Professor, 金属材料研究所, 助教授 (20134041)
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| Co-Investigator(Kenkyū-buntansha) |
SHINDO Tiasuke Tohoku University, Institute of Multidisciplinary Research, Professor, 多元物質科学研究所, 教授 (20154396)
GOTO Takashi Tohoku University, Institute for Materials Research, Professor, 金属材料研究所, 教授 (60125549)
ABE Takao Shin-Etsu Handoutai, Chief Researcher, 半導体研究所, 研究主幹
SAKURAI Masaki Tohoku University, Institute for Materials Research, Research Associate, 金属材料研究所, 助手 (80235225)
AKASHI Takaya Tohoku University, Institute for Materials Research, Research Associate, 金属材料研究所, 助手 (20312647)
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| Project Period (FY) |
2001 – 2003
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| Keywords | Germanium-Silicon / Solid Solution / Single Crystal Growth / Fundamental Properties / X-ray Absorption Fine Structure / Impurities / Lattice Defects / Thermo-Electrics |
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| Research Abstract |
Germanium-silicon (Ge_<1-x>Si_x or Germanium-silicon Si_xGe_<1-x>) alloy is a fully miscible solid solution of the diamond-base and has attracted keen interest as material for both microelectronic and opto-electronic devices in view of the potential for band gap and lattice parameter engineering they offer. This research has been undertaken in order to establish the growth of high quality single crystals of GeSi alloys and to clarify the various fundamental properties that are brought about by alloying and the possibility of exploring the intrinsic properties and potentials of this material for wide applications.
(1)Full single crystals of large size, larger than 25 mm in diameter and longer than 40 mm in length, were obtained for the alloys of composition 0<x<0.15 and 0.73<x<1 by the Czochralski technique. Single crystals of SiGe alloys (0.80<x<1) heavily doped with electrically active impurities with a concentration up to 10^<20>cm^<-3> were also successfully obtained.
(2)By XAFS study
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on the local atomic structure, it is known that GeSi alloy possess random substitutional site occupancy of Si and Ge atoms but no preferential ordering across the whole composition range and that Ge-Ge and Ge-Si bond lengths maintain distinctly different lengths and vary linearly with alloy composition, to he incomplete Pauling case.
(3)Oxygen impurities in the concentration of 10^<18>cm^<-3> maximum occupy preferentially a bond-center site between Si atoms to make a Si-O-Si quasi-molecule.
(4)The mechanical strength of the alloys becomes temperature-insensitive at elevated temperatures and depends on the composition, being proportional to x(1-x) over the whole composition range, which may be originating in the built-in stress fields related to microscopic fluctuation of alloy composition and the dynamic interaction between dislocations.
(5)Electrical and thermal conductivities and Seebeck coefficient in heavily impurity doped GeSi were evaluated for develop thermoelectric converters available at elevated temperatures. Less
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Research Products
(12 results)
