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Amorphous and polysilicon devices

  • Avner Friedman
Part of the The IMA Volumes in Mathematics and its Applications book series (IMA, volume 57)

Abstract

Polysilicon is made up of silicon grains, each grain being a crystal in which the silicon atoms are arranged in a periodic structure. The distance between 0 two silicon atoms in the crystal is 2 – 3 Å, and the typical size of a grain in polysilicon is 1, 000 – 10, 000 Å. Thus each grain contains many millions of atoms. On the other hand, in amorphous silicon the atoms are typically grouped in 4 – 6 atoms, and there is no discerned periodic structure. In order to pacify the dangling bonds some hydrogen is added (approximately 20%); this is called hydrodegenation. Amorphous silicon is relatively easy to make, and it can be deposited on a large area. Polysilicon is harder to deposit on a large area; and pure silicon crystals are still harder to deposit (and more expensive), being more readily susceptible to faults. Amorphous silicon is a poor conductor, and is therefore not used in high-speed computer chips. Thin-film transistors (TFTs) fabricated from hydrogenated amorphous silicon (a — Si) and polycrystalline silicon (polysilicon, poly-Si) are now used in many commercial large-area electronic applications such as in flat panel display, printing and scanning (e.g., in fax machines).

Keywords

Silicon Atom Amorphous Silicon Polycrystalline Silicon Trap Charge Flat Panel Display 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag New York, Inc. 1994

Authors and Affiliations

  • Avner Friedman
    • 1
  1. 1.Institute for Mathematics and its ApplicationsUniversity of MinnesotaMinneapolisUSA

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