Mathematics in Industrial Problems pp 52-60 | Cite as

# Amorphous and polysilicon devices

## 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

Recombination Lution Polysilicon## Preview

Unable to display preview. Download preview PDF.

### References

- [1]P.A. Markowich, C.A. Ringhofer and C. Schmeiser,
*Semiconductor Equations*, Springer-Verlag, Vienna (1990).MATHCrossRefGoogle Scholar - [2]J.G. Shaw, M. Hack and R.A. Martin, Meta-stable
*changes in the*output*characteristics of high-voltage*amorphous*silicon thin-film*transistors, J. Non-Crystalline Solids, 115 (1989), 141–143.CrossRefGoogle Scholar - [3]J.G. Shaw and M. Hack, Vertical amorphous
*silicon thin-film transistors*, J. Appl. Phys., 67 (1990), 1576–1581.CrossRefGoogle Scholar - [4]J.G. Shaw, M.G. Hack and R.A. Martin, Metastable effects
*in high-voltage amorphous silicon thin-film transistors*, J. Appl. Phys., 69 (1991), 2667–2672.CrossRefGoogle Scholar - [5]J.G. Shaw and M. Hack,
*An analytic model for calculating trapped charge in amorphous silicon*, J. Appl. Phys., 64 (1988), 4562–4566.CrossRefGoogle Scholar - [6]J.G. Shaw, P.G. LeComber and M. Williams,
*Density-of-states and transient simulations of amorphous-silicon devices. J.*Non-Crystalline Solids, 137 & 138 (1991), 1233–1236.CrossRefGoogle Scholar - [7]J.G. Shaw and M.G. Hack,
*Simulation and modeling of amorphous silicon thin-film devices*, to appear.Google Scholar - [8]S.M. Sze,
*Physics of Semiconductor Devices*, Wiley, New York (1981).Google Scholar - [9]S. Selberherr,
*Analysis and Simulation of Semiconductor Devices*, Springer-Verlag, Vienna (1984).Google Scholar - [10]M.S. Mock,
*Analysis*of Mathematical*Models of Semiconductor Devices*, Boole Press, Dublin (1983).Google Scholar - [11]H. Gajewski,
*On*existence,*uniqueness and asymptotic behavior of solutions of the basic*equations*for carrier transport in semiconductors*,Zamm. Z. Angew. Math. Mech., 65 (1985), 101–108.MathSciNetMATHCrossRefGoogle Scholar