Abstract

The response of extrinsic photoconductors to a step change in incident photon flux has long been known to exhibit a sharp transient feature, particularly at higher signal levels, known as the hook effect. We demonstrate experimentally and theoretically that the hook effect can be due to reduced illumination adjacent to the injecting contact. This nonuniformity can be produced by the transverse illumination of the detector that is common for far-infrared Ge:Ga devices. The hook effect has been demonstrated to be either present or absent in the same Ge:Ga photoconductor, at comparable signal size, depending on the nature of the contact illumination. Numerical finite-difference calculations of the transient response support this explanation and produce features that replicate the experimental results.

© 2001 Optical Society of America

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References

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  1. R. L. Williams, “Relaxation phenomena in high resistivity Ge:Hg,” J. Appl. Phys. 38, 4802–4806 (1967).
    [CrossRef]
  2. R. L. Williams, “Response characteristics of extrinsic photoconductors,” J. Appl. Phys. 40, 184–192 (1969).
    [CrossRef]
  3. R. A. Suris, B. I. Fouks, “Theory of nonlinear transient processes in compensated semiconductors,” Sov. Phys. Semicond. 14, 896–901 (1980).
  4. L. A. Vinokurov, B. I. Fouks, “Nonlinear photoresponse in extrinsic photoconductors,” Sov. Phys. Semicond. 25, 1207–1211 (1991).
  5. B. I. Fouks, “Nonstationary behavior of low background photon detectors,” in Proceedings of the European Space Agency Symposium on Photon Detectors for Space Instrumentation, SP-356 (European Space Agency, Noordwijk, The Netherlands, 1993), pp. 167–174, and references therein.
  6. N. M. Haegel, D. R. Palmieri, A. M. White, “Current transients in extrinsic photoconductors: comprehensive analytical description of initial response,” Appl. Phys. A 73, 433–439 (2001).
    [CrossRef]
  7. N. M. Haegel, C. R. Brennan, A. M. White, “Transport in extrinsic photoconductors: a comprehensive model for transient response,” J. Appl. Phys. 80, 1510–1514 (1996).
    [CrossRef]
  8. N. M. Haegel, J. C. Simoes, A. M. White, J. W. Beeman, “Transient behavior of infrared photoconductors: application of a numerical model,” Appl. Opt. 38, 1910–1919 (1999).
    [CrossRef]
  9. P. R. Bratt, “Impurity germanium and silicon infrared detectors,” in Semiconductors and Semimetals, R. K. Willardson, A. C. Beer, eds. (Academic, New York, 1977), Vol. 12, pp. 39–142.
    [CrossRef]
  10. V. F. Kocherov, I. I. Taubkin, N. B. Zaletaev, “Extrinsic silicon and germanium detectors,” in Infrared Photon Detectors, A. Rogalski, ed., Vol. PM20 of the SPIE Press Monographs (SPIE, Bellingham Wash., 1995), Chap. 8, pp. 189–297.
  11. See http://sirtf.caltech.edu for mission and instruments overviews.
  12. A. M. White, “The characteristics of minority carrier exclusion in narrow direct-gap semiconductors,” Infrared Phys. 25, 729–741 (1985).
    [CrossRef]
  13. S. E. Church, M. C. Price, N. M. Haegel, M. J. Griffin, P. A. R. Ade, “Transient response in doped germanium photoconductors under very low background operation,” Appl. Opt. 35, 1597–1604 (1996).
    [CrossRef] [PubMed]
  14. A. Coulais, A. Abergel, “Transient correction of the LW-ISOCAM data for low contrasted illumination,” Astron. Astrophys. Suppl. Ser. 141, 533–544 (2000).
    [CrossRef]

2001 (1)

N. M. Haegel, D. R. Palmieri, A. M. White, “Current transients in extrinsic photoconductors: comprehensive analytical description of initial response,” Appl. Phys. A 73, 433–439 (2001).
[CrossRef]

2000 (1)

A. Coulais, A. Abergel, “Transient correction of the LW-ISOCAM data for low contrasted illumination,” Astron. Astrophys. Suppl. Ser. 141, 533–544 (2000).
[CrossRef]

1999 (1)

1996 (2)

N. M. Haegel, C. R. Brennan, A. M. White, “Transport in extrinsic photoconductors: a comprehensive model for transient response,” J. Appl. Phys. 80, 1510–1514 (1996).
[CrossRef]

S. E. Church, M. C. Price, N. M. Haegel, M. J. Griffin, P. A. R. Ade, “Transient response in doped germanium photoconductors under very low background operation,” Appl. Opt. 35, 1597–1604 (1996).
[CrossRef] [PubMed]

1991 (1)

L. A. Vinokurov, B. I. Fouks, “Nonlinear photoresponse in extrinsic photoconductors,” Sov. Phys. Semicond. 25, 1207–1211 (1991).

1985 (1)

A. M. White, “The characteristics of minority carrier exclusion in narrow direct-gap semiconductors,” Infrared Phys. 25, 729–741 (1985).
[CrossRef]

1980 (1)

R. A. Suris, B. I. Fouks, “Theory of nonlinear transient processes in compensated semiconductors,” Sov. Phys. Semicond. 14, 896–901 (1980).

1969 (1)

R. L. Williams, “Response characteristics of extrinsic photoconductors,” J. Appl. Phys. 40, 184–192 (1969).
[CrossRef]

1967 (1)

R. L. Williams, “Relaxation phenomena in high resistivity Ge:Hg,” J. Appl. Phys. 38, 4802–4806 (1967).
[CrossRef]

Abergel, A.

A. Coulais, A. Abergel, “Transient correction of the LW-ISOCAM data for low contrasted illumination,” Astron. Astrophys. Suppl. Ser. 141, 533–544 (2000).
[CrossRef]

Ade, P. A. R.

Beeman, J. W.

Bratt, P. R.

P. R. Bratt, “Impurity germanium and silicon infrared detectors,” in Semiconductors and Semimetals, R. K. Willardson, A. C. Beer, eds. (Academic, New York, 1977), Vol. 12, pp. 39–142.
[CrossRef]

Brennan, C. R.

N. M. Haegel, C. R. Brennan, A. M. White, “Transport in extrinsic photoconductors: a comprehensive model for transient response,” J. Appl. Phys. 80, 1510–1514 (1996).
[CrossRef]

Church, S. E.

Coulais, A.

A. Coulais, A. Abergel, “Transient correction of the LW-ISOCAM data for low contrasted illumination,” Astron. Astrophys. Suppl. Ser. 141, 533–544 (2000).
[CrossRef]

Fouks, B. I.

L. A. Vinokurov, B. I. Fouks, “Nonlinear photoresponse in extrinsic photoconductors,” Sov. Phys. Semicond. 25, 1207–1211 (1991).

R. A. Suris, B. I. Fouks, “Theory of nonlinear transient processes in compensated semiconductors,” Sov. Phys. Semicond. 14, 896–901 (1980).

B. I. Fouks, “Nonstationary behavior of low background photon detectors,” in Proceedings of the European Space Agency Symposium on Photon Detectors for Space Instrumentation, SP-356 (European Space Agency, Noordwijk, The Netherlands, 1993), pp. 167–174, and references therein.

Griffin, M. J.

Haegel, N. M.

N. M. Haegel, D. R. Palmieri, A. M. White, “Current transients in extrinsic photoconductors: comprehensive analytical description of initial response,” Appl. Phys. A 73, 433–439 (2001).
[CrossRef]

N. M. Haegel, J. C. Simoes, A. M. White, J. W. Beeman, “Transient behavior of infrared photoconductors: application of a numerical model,” Appl. Opt. 38, 1910–1919 (1999).
[CrossRef]

S. E. Church, M. C. Price, N. M. Haegel, M. J. Griffin, P. A. R. Ade, “Transient response in doped germanium photoconductors under very low background operation,” Appl. Opt. 35, 1597–1604 (1996).
[CrossRef] [PubMed]

N. M. Haegel, C. R. Brennan, A. M. White, “Transport in extrinsic photoconductors: a comprehensive model for transient response,” J. Appl. Phys. 80, 1510–1514 (1996).
[CrossRef]

Kocherov, V. F.

V. F. Kocherov, I. I. Taubkin, N. B. Zaletaev, “Extrinsic silicon and germanium detectors,” in Infrared Photon Detectors, A. Rogalski, ed., Vol. PM20 of the SPIE Press Monographs (SPIE, Bellingham Wash., 1995), Chap. 8, pp. 189–297.

Palmieri, D. R.

N. M. Haegel, D. R. Palmieri, A. M. White, “Current transients in extrinsic photoconductors: comprehensive analytical description of initial response,” Appl. Phys. A 73, 433–439 (2001).
[CrossRef]

Price, M. C.

Simoes, J. C.

Suris, R. A.

R. A. Suris, B. I. Fouks, “Theory of nonlinear transient processes in compensated semiconductors,” Sov. Phys. Semicond. 14, 896–901 (1980).

Taubkin, I. I.

V. F. Kocherov, I. I. Taubkin, N. B. Zaletaev, “Extrinsic silicon and germanium detectors,” in Infrared Photon Detectors, A. Rogalski, ed., Vol. PM20 of the SPIE Press Monographs (SPIE, Bellingham Wash., 1995), Chap. 8, pp. 189–297.

Vinokurov, L. A.

L. A. Vinokurov, B. I. Fouks, “Nonlinear photoresponse in extrinsic photoconductors,” Sov. Phys. Semicond. 25, 1207–1211 (1991).

White, A. M.

N. M. Haegel, D. R. Palmieri, A. M. White, “Current transients in extrinsic photoconductors: comprehensive analytical description of initial response,” Appl. Phys. A 73, 433–439 (2001).
[CrossRef]

N. M. Haegel, J. C. Simoes, A. M. White, J. W. Beeman, “Transient behavior of infrared photoconductors: application of a numerical model,” Appl. Opt. 38, 1910–1919 (1999).
[CrossRef]

N. M. Haegel, C. R. Brennan, A. M. White, “Transport in extrinsic photoconductors: a comprehensive model for transient response,” J. Appl. Phys. 80, 1510–1514 (1996).
[CrossRef]

A. M. White, “The characteristics of minority carrier exclusion in narrow direct-gap semiconductors,” Infrared Phys. 25, 729–741 (1985).
[CrossRef]

Williams, R. L.

R. L. Williams, “Response characteristics of extrinsic photoconductors,” J. Appl. Phys. 40, 184–192 (1969).
[CrossRef]

R. L. Williams, “Relaxation phenomena in high resistivity Ge:Hg,” J. Appl. Phys. 38, 4802–4806 (1967).
[CrossRef]

Zaletaev, N. B.

V. F. Kocherov, I. I. Taubkin, N. B. Zaletaev, “Extrinsic silicon and germanium detectors,” in Infrared Photon Detectors, A. Rogalski, ed., Vol. PM20 of the SPIE Press Monographs (SPIE, Bellingham Wash., 1995), Chap. 8, pp. 189–297.

Appl. Opt. (2)

Appl. Phys. A (1)

N. M. Haegel, D. R. Palmieri, A. M. White, “Current transients in extrinsic photoconductors: comprehensive analytical description of initial response,” Appl. Phys. A 73, 433–439 (2001).
[CrossRef]

Astron. Astrophys. Suppl. Ser. (1)

A. Coulais, A. Abergel, “Transient correction of the LW-ISOCAM data for low contrasted illumination,” Astron. Astrophys. Suppl. Ser. 141, 533–544 (2000).
[CrossRef]

Infrared Phys. (1)

A. M. White, “The characteristics of minority carrier exclusion in narrow direct-gap semiconductors,” Infrared Phys. 25, 729–741 (1985).
[CrossRef]

J. Appl. Phys. (3)

N. M. Haegel, C. R. Brennan, A. M. White, “Transport in extrinsic photoconductors: a comprehensive model for transient response,” J. Appl. Phys. 80, 1510–1514 (1996).
[CrossRef]

R. L. Williams, “Relaxation phenomena in high resistivity Ge:Hg,” J. Appl. Phys. 38, 4802–4806 (1967).
[CrossRef]

R. L. Williams, “Response characteristics of extrinsic photoconductors,” J. Appl. Phys. 40, 184–192 (1969).
[CrossRef]

Sov. Phys. Semicond. (2)

R. A. Suris, B. I. Fouks, “Theory of nonlinear transient processes in compensated semiconductors,” Sov. Phys. Semicond. 14, 896–901 (1980).

L. A. Vinokurov, B. I. Fouks, “Nonlinear photoresponse in extrinsic photoconductors,” Sov. Phys. Semicond. 25, 1207–1211 (1991).

Other (4)

B. I. Fouks, “Nonstationary behavior of low background photon detectors,” in Proceedings of the European Space Agency Symposium on Photon Detectors for Space Instrumentation, SP-356 (European Space Agency, Noordwijk, The Netherlands, 1993), pp. 167–174, and references therein.

P. R. Bratt, “Impurity germanium and silicon infrared detectors,” in Semiconductors and Semimetals, R. K. Willardson, A. C. Beer, eds. (Academic, New York, 1977), Vol. 12, pp. 39–142.
[CrossRef]

V. F. Kocherov, I. I. Taubkin, N. B. Zaletaev, “Extrinsic silicon and germanium detectors,” in Infrared Photon Detectors, A. Rogalski, ed., Vol. PM20 of the SPIE Press Monographs (SPIE, Bellingham Wash., 1995), Chap. 8, pp. 189–297.

See http://sirtf.caltech.edu for mission and instruments overviews.

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Figures (8)

Fig. 1
Fig. 1

Example of hook response in a Ge:Ga photoconductor at T ∼ 2.5 K.

Fig. 2
Fig. 2

Simulated transient response for a uniformly and nonuniformly illuminated detector, with Δg (signal) = g (background). The nonuniform condition is an 85% reduction of flux in a region of 166 µm adjacent to the injecting contact. Results are presented on (a) linear and (b) logarithmic time scales.

Fig. 3
Fig. 3

Simulated transient response for the nonuniform illumination condition as a function of signal size. The magnitude and time constant for the hook response change as a function of signal size. Results are presented on (a) linear and (b) logarithmic time scales.

Fig. 4
Fig. 4

Change in electric field (V/cm) as a function of position between the contacts and time. Time is plotted on a logarithmic scale. The transient increase in field in the nonuniformly illuminated region (0–166 µm) is connected to a transient decrease in field in the remainder of the device.

Fig. 5
Fig. 5

Change in hole current (A/cm2) as a function of position between the contacts and time. Time is plotted on a logarithmic scale. The transient decrease in hole current (drift plus diffusion) over a majority of the device gives rise to a decrease in total current (drift plus diffusion plus displacement) that is observed as the hook effect.

Fig. 6
Fig. 6

Comparison of the experimental transient result for transverse and transparent contact illumination on the same device. Applied field is 0.5 V/cm.

Fig. 7
Fig. 7

Transient response for a series of signals (signal sizes from 10 to 50 mV) for transverse illumination. Applied field is 1.0 V/cm.

Fig. 8
Fig. 8

Transient response for a series of signals (signal sizes from 20 to 70 mV) for illumination through a transparent contact. Applied field is 0.5 V/cm.

Tables (1)

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Table 1 Modeling Parameters for Ge:Gaa

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