Parameters Affecting Light-Induced Excess Conductivity in Amorphous Silicon Doping-Modulated Multilayers

Abstract

The phenomenon of light-induced excess conductivity (LEC) which occurs in a-Si:H npnp doping-modulated multilayers is found experimentally to be dependent on several different factors. The concentrations of the dopants in n-type and p-type layers affect the Fermi level position, the height of the barriers, and also the density of defects. These parameters are altered by different choices of inert gas diluent (Ar or He) and substrate temperature Ts. For a given set of deposition conditions, the LEC effect can be maximized by varying the layer thickness. With undiluted silane at Ts = 250 °C, the effect was relatively small, reaching a maximum in relatively thick layers (540 Å). The largest effects were obtained for films deposited from silane diluted in helium, using thinner (330 Å) layers. However, for films deposited from silane diluted in argon, the magnitude of the effect and optimum layer thickness was intermediate (440 Å). When Ts was varied, a minimum in LEC was found near 200–250° C. The influence of internal field was examined by using nini, pipi and npnp multilayers. The internal field is a necessary factor to observe a large LEC effect. A compensated film shows a small LEC effect.

This is a preview of subscription content, access via your institution.

References

  1. 1.

    J. Kakalios and H. Fritzsche, Phys. Rev. Lett. 53, 1602 (1984)

    CAS  Article  Google Scholar 

  2. 2.

    M. Hundhausen and L. Ley, Phys. Rev. B32, 6655 (1985)

    Article  Google Scholar 

  3. 3.

    S. C. Agarwal and S. Guha, Phys. Rev. B32, 8469 (1985)

    Article  Google Scholar 

  4. 4.

    F.-C. Su, S. Levine, P. E. Vanier and F. J. Kampas, J. Appl. Phys. 59, 2168 (1986)

    CAS  Article  Google Scholar 

  5. 5.

    G. H. Dohler, H. Kunzel and K. Ploog, Phys. Rev. B25, 2616 (1982)

    Article  Google Scholar 

  6. 6.

    B. A. Scott, J. A. Reimer and P. A. Longeway, J. Appl. Phys. 54, 6853 (1983)

    CAS  Article  Google Scholar 

  7. 7.

    J. A. Reimer, R. W. Vaughan and J. C. Knights, Phys. Rev. B24, 3360 (1981)

    Article  Google Scholar 

  8. 8.

    J. M. Marshall, R. A. Street and M. J. Thompson, J. Non-Cryst, Solids 66, 175 (1984)

    CAS  Article  Google Scholar 

Download references

Author information

Affiliations

Authors

Corresponding author

Correspondence to F.-C. Su.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Su, FC., Levine, S. & Vanier, P.E. Parameters Affecting Light-Induced Excess Conductivity in Amorphous Silicon Doping-Modulated Multilayers. MRS Online Proceedings Library 70, 447–452 (1986). https://doi.org/10.1557/PROC-70-447

Download citation