Negative differential photoconductivity of thin graded-bandgap layers in conditions of carrier extraction effect

Bogdan S. Sokolovsky; Volodymyr K. Pysarevsky; Oleksiy V. Nemolovsky

doi:10.1117/12.417764

22 February 2001 Negative differential photoconductivity of thin graded-bandgap layers in conditions of carrier extraction effect

Bogdan S. Sokolovsky, Volodymyr K. Pysarevsky, Oleksiy V. Nemolovsky

Author Affiliations +

Proceedings Volume 4355, Fifth International Conference on Material Science and Material Properties for Infrared Optoelectronics; (2001) https://doi.org/10.1117/12.417764
Event: Fifth International Conference on Material Science and Material Properties for Infrared Optoelectronics, 2000, Kiev, Ukraine

Abstract

The paper theoretically examines the peculiarities of photoconductivity of thin graded-band-gap layers with linear profile of energy gap and Ohmic contacts. It is analyzed in detail the cases of illumination of the layers from wide gap side by polychromatic light with spatially constant carrier photogeneration function and by strongly absorbed monochromatic light. Carrier extraction effect is shown to cause strong nonmonotonous field dependence of effective lifetime in the case of thin layers. The maximum of carrier effective lifetime is reached when the total force acting on photocarriers is equal (in the case of bulk photoexcitation) or close (in the case of local photogeneration function) to zero. Such a field dependence of effective lifetime can lead to formation of negative differential photoconductivity of N- type. The photo-current peak occurs at the external field strength approximately equals to that of quasielectric field in the case of layer thickness comparable with the minority carrier length and at the substantially stronger fields in the case of very thin films.

Citation Download Citation

Bogdan S. Sokolovsky, Volodymyr K. Pysarevsky, and Oleksiy V. Nemolovsky "Negative differential photoconductivity of thin graded-bandgap layers in conditions of carrier extraction effect", Proc. SPIE 4355, Fifth International Conference on Material Science and Material Properties for Infrared Optoelectronics, (22 February 2001); https://doi.org/10.1117/12.417764

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