Silicon-Based Materials --Syntheses and Properties--
Silicon backbone materials as illustrated in Fig. 1 show
interesting opto-electronic properties, depending on their backbone
geometry. We have been focusing on these materials and investigating
their physical properties.
The silicon backbone of these materials corresponds to a part of the crystalline silicon. It is interesting to realize how the semiconducting property of the silicon materials is varied based on their geometry structure. In our studies, we found that the band gap is extended over the range from 1.1 eV to 4.5 eV, as the backbone structure varies crystalline (3-dimensional), sheet-like (2-dimensional), and chain-like (1-dimensional). In contrast to the nonradiavative crystalline silicon, the chain- and sheet-like silicon materials emit intense light in the UV and visible region.
A conventional method to synthesize a chain-like polysilane is
the chemical reduction of organo-substituted dichlorosilanes,
R1R2SiCl2, with alkali metals.
We have applied this reaction to organotrichlorosilanes, RSiCl3,
which has yielded silicon network polymers
with a sheet-like silicon backbones 
and an octasilacubane with a cubic silicon backbone of Si8 .
Regular hetero-copolymers with other group 14 elements have also been
prepared from well-designed starting materials .
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 K. Furukawa et al., Appl. Phys. Lett., 60 (1992) 2744-5.
 H. Isaka et al., Macromolecules, 24 (1991) 2647-8.