Abstract

A numerical model for the transient response of extrinsic photoconductors is applied to the behavior of Ge:Ga and GaAs:Te detectors. Photoconductors display a two-component response to changes in illumination. The characteristic time and magnitude for the slow component have been studied as a function of background flux, applied field, temperature, device length, and signal size. For large-signal applications, the background flux affects the transient response even when the signal is orders of magnitude greater than the background. Experimental results are presented to support key predictions of the modeling. Because the ratio of fast to slow components is independent of both background and signal size, we propose the operation of detectors in such a way that final signal levels are derived from the fast component.

© 1999 Optical Society of America

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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. A. Fenner Milton and M. M. Blouke, “Sweepout and dielectric relaxation in compensated extrinsic photoconductors,” Phys. Rev. B 3, 4312–4330 (1971).
    [CrossRef]
  4. 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]
  5. 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]
  6. R. M. Westervelt, S. W. Teitsworth, “Nonlinear transient response of extrinsic Ge far-infrared photoconductors,” J. Appl. Phys. 57, 5457–5469 (1985).
    [CrossRef]
  7. B. I. Fouks, “Injection properties of contacts to high-resistivity semiconductors,” Sov. Phys. Semicond. 15, 974–986 (1981). [Fix. Tekh. Poluprov. 15, 1679–1690 (1981)].
  8. B. I. Fouks, “Non-stationary behavior of low background photon detectors,” in Proceedings of the European Space Agency Symposium on Photon Detectors for Space Instrumentation (European Space Agency, Noordwijk, 1993) SP-356, pp. 167–174, and references therein.
  9. B. I. Fouks, “Theory of photoresponse of low-background IR detectors,” in Infrared Spaceborne Remote Sensing V, M. S. Scholl, B. Andresen, eds., Proc. SPIE3122, 441–452 (1997).
    [CrossRef]
  10. A. Moneti, “Infrared Space Observatory (ISO) detector workshop: viewgraphs of the presentations,” presented at the ISO Detector Workshop, Villafranca del Castillo, Spain, 14–16 January 1998.
  11. N. M. Haegel, A. M. White, “Modeling of near-contact field and carrier distributions in extrinsic photoconductors,” Infrared Phys. 29, 915–923 (1989).
    [CrossRef]
  12. N. M. Haegel, C. A. Latasa, A. M. White, “Transient response of infrared photoconductors: the roles of contacts and space charge,” Appl. Phys. A 56, 15–21 (1993).
    [CrossRef]
  13. 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]
  14. N. M. Haegel, C. Newton, J. C. Simoes, A. M. White, “Modeling of transient response in far infrared photoconductors,” in Proceedings of the European Space Agency Symposium on Submillimetre and Far-Infrared Space Instrumentation (European Space Agency, Noordwijk, 1996) SP-388, pp. 15–21.
  15. A. M. White, “The characteristics of minority carrier exclusion in narrow direct-gap semiconductors,” Infrared Phys. 25, 729–741 (1985).
    [CrossRef]
  16. N. M. Haegel, J. W. Beeman, P. N. Luke, E. E. Haller, “Transient photoconductivity in Ge:Be due to Be+ formation,” Phys. Rev. B 39, 3677–3682 (1989).
    [CrossRef]

1996 (2)

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]

1993 (1)

N. M. Haegel, C. A. Latasa, A. M. White, “Transient response of infrared photoconductors: the roles of contacts and space charge,” Appl. Phys. A 56, 15–21 (1993).
[CrossRef]

1989 (2)

N. M. Haegel, J. W. Beeman, P. N. Luke, E. E. Haller, “Transient photoconductivity in Ge:Be due to Be+ formation,” Phys. Rev. B 39, 3677–3682 (1989).
[CrossRef]

N. M. Haegel, A. M. White, “Modeling of near-contact field and carrier distributions in extrinsic photoconductors,” Infrared Phys. 29, 915–923 (1989).
[CrossRef]

1985 (2)

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

R. M. Westervelt, S. W. Teitsworth, “Nonlinear transient response of extrinsic Ge far-infrared photoconductors,” J. Appl. Phys. 57, 5457–5469 (1985).
[CrossRef]

1981 (1)

B. I. Fouks, “Injection properties of contacts to high-resistivity semiconductors,” Sov. Phys. Semicond. 15, 974–986 (1981). [Fix. Tekh. Poluprov. 15, 1679–1690 (1981)].

1971 (1)

A. Fenner Milton and M. M. Blouke, “Sweepout and dielectric relaxation in compensated extrinsic photoconductors,” Phys. Rev. B 3, 4312–4330 (1971).
[CrossRef]

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]

Ade, P. A. R.

Beeman, J. W.

N. M. Haegel, J. W. Beeman, P. N. Luke, E. E. Haller, “Transient photoconductivity in Ge:Be due to Be+ formation,” Phys. Rev. B 39, 3677–3682 (1989).
[CrossRef]

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.

Fenner Milton and M. M. Blouke, A.

A. Fenner Milton and M. M. Blouke, “Sweepout and dielectric relaxation in compensated extrinsic photoconductors,” Phys. Rev. B 3, 4312–4330 (1971).
[CrossRef]

Fouks, B. I.

B. I. Fouks, “Injection properties of contacts to high-resistivity semiconductors,” Sov. Phys. Semicond. 15, 974–986 (1981). [Fix. Tekh. Poluprov. 15, 1679–1690 (1981)].

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

B. I. Fouks, “Theory of photoresponse of low-background IR detectors,” in Infrared Spaceborne Remote Sensing V, M. S. Scholl, B. Andresen, eds., Proc. SPIE3122, 441–452 (1997).
[CrossRef]

Griffin, M. J.

Haegel, N. M.

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]

N. M. Haegel, C. A. Latasa, A. M. White, “Transient response of infrared photoconductors: the roles of contacts and space charge,” Appl. Phys. A 56, 15–21 (1993).
[CrossRef]

N. M. Haegel, J. W. Beeman, P. N. Luke, E. E. Haller, “Transient photoconductivity in Ge:Be due to Be+ formation,” Phys. Rev. B 39, 3677–3682 (1989).
[CrossRef]

N. M. Haegel, A. M. White, “Modeling of near-contact field and carrier distributions in extrinsic photoconductors,” Infrared Phys. 29, 915–923 (1989).
[CrossRef]

N. M. Haegel, C. Newton, J. C. Simoes, A. M. White, “Modeling of transient response in far infrared photoconductors,” in Proceedings of the European Space Agency Symposium on Submillimetre and Far-Infrared Space Instrumentation (European Space Agency, Noordwijk, 1996) SP-388, pp. 15–21.

Haller, E. E.

N. M. Haegel, J. W. Beeman, P. N. Luke, E. E. Haller, “Transient photoconductivity in Ge:Be due to Be+ formation,” Phys. Rev. B 39, 3677–3682 (1989).
[CrossRef]

Latasa, C. A.

N. M. Haegel, C. A. Latasa, A. M. White, “Transient response of infrared photoconductors: the roles of contacts and space charge,” Appl. Phys. A 56, 15–21 (1993).
[CrossRef]

Luke, P. N.

N. M. Haegel, J. W. Beeman, P. N. Luke, E. E. Haller, “Transient photoconductivity in Ge:Be due to Be+ formation,” Phys. Rev. B 39, 3677–3682 (1989).
[CrossRef]

Moneti, A.

A. Moneti, “Infrared Space Observatory (ISO) detector workshop: viewgraphs of the presentations,” presented at the ISO Detector Workshop, Villafranca del Castillo, Spain, 14–16 January 1998.

Newton, C.

N. M. Haegel, C. Newton, J. C. Simoes, A. M. White, “Modeling of transient response in far infrared photoconductors,” in Proceedings of the European Space Agency Symposium on Submillimetre and Far-Infrared Space Instrumentation (European Space Agency, Noordwijk, 1996) SP-388, pp. 15–21.

Price, M. C.

Simoes, J. C.

N. M. Haegel, C. Newton, J. C. Simoes, A. M. White, “Modeling of transient response in far infrared photoconductors,” in Proceedings of the European Space Agency Symposium on Submillimetre and Far-Infrared Space Instrumentation (European Space Agency, Noordwijk, 1996) SP-388, pp. 15–21.

Teitsworth, S. W.

R. M. Westervelt, S. W. Teitsworth, “Nonlinear transient response of extrinsic Ge far-infrared photoconductors,” J. Appl. Phys. 57, 5457–5469 (1985).
[CrossRef]

Westervelt, R. M.

R. M. Westervelt, S. W. Teitsworth, “Nonlinear transient response of extrinsic Ge far-infrared photoconductors,” J. Appl. Phys. 57, 5457–5469 (1985).
[CrossRef]

White, A. M.

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]

N. M. Haegel, C. A. Latasa, A. M. White, “Transient response of infrared photoconductors: the roles of contacts and space charge,” Appl. Phys. A 56, 15–21 (1993).
[CrossRef]

N. M. Haegel, A. M. White, “Modeling of near-contact field and carrier distributions in extrinsic photoconductors,” Infrared Phys. 29, 915–923 (1989).
[CrossRef]

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

N. M. Haegel, C. Newton, J. C. Simoes, A. M. White, “Modeling of transient response in far infrared photoconductors,” in Proceedings of the European Space Agency Symposium on Submillimetre and Far-Infrared Space Instrumentation (European Space Agency, Noordwijk, 1996) SP-388, pp. 15–21.

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]

Appl. Opt. (1)

Appl. Phys. A (1)

N. M. Haegel, C. A. Latasa, A. M. White, “Transient response of infrared photoconductors: the roles of contacts and space charge,” Appl. Phys. A 56, 15–21 (1993).
[CrossRef]

Infrared Phys. (2)

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

N. M. Haegel, A. M. White, “Modeling of near-contact field and carrier distributions in extrinsic photoconductors,” Infrared Phys. 29, 915–923 (1989).
[CrossRef]

J. Appl. Phys. (4)

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. M. Westervelt, S. W. Teitsworth, “Nonlinear transient response of extrinsic Ge far-infrared photoconductors,” J. Appl. Phys. 57, 5457–5469 (1985).
[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]

Phys. Rev. B (2)

A. Fenner Milton and M. M. Blouke, “Sweepout and dielectric relaxation in compensated extrinsic photoconductors,” Phys. Rev. B 3, 4312–4330 (1971).
[CrossRef]

N. M. Haegel, J. W. Beeman, P. N. Luke, E. E. Haller, “Transient photoconductivity in Ge:Be due to Be+ formation,” Phys. Rev. B 39, 3677–3682 (1989).
[CrossRef]

Sov. Phys. Semicond. (1)

B. I. Fouks, “Injection properties of contacts to high-resistivity semiconductors,” Sov. Phys. Semicond. 15, 974–986 (1981). [Fix. Tekh. Poluprov. 15, 1679–1690 (1981)].

Other (5)

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

B. I. Fouks, “Theory of photoresponse of low-background IR detectors,” in Infrared Spaceborne Remote Sensing V, M. S. Scholl, B. Andresen, eds., Proc. SPIE3122, 441–452 (1997).
[CrossRef]

A. Moneti, “Infrared Space Observatory (ISO) detector workshop: viewgraphs of the presentations,” presented at the ISO Detector Workshop, Villafranca del Castillo, Spain, 14–16 January 1998.

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]

N. M. Haegel, C. Newton, J. C. Simoes, A. M. White, “Modeling of transient response in far infrared photoconductors,” in Proceedings of the European Space Agency Symposium on Submillimetre and Far-Infrared Space Instrumentation (European Space Agency, Noordwijk, 1996) SP-388, pp. 15–21.

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Figures (11)

Fig. 1
Fig. 1

Spatial and temporal distribution of changes in (a) carrier concentration, (b) electric field, (c) total current for a 400-µm GaAs:Te photoconductor. Modeling parameters are given in Table 1. Note that the direction of the time axis is reversed in (b) for better viewing.

Fig. 2
Fig. 2

Spatial and temporal distribution of changes in (a) carrier concentration, (b) electric field, (c) total current for a 75-µm GaAs:Te photoconductor. Modeling parameters are given in Table 1. Note that the direction of the time axis is reversed in (b) for better viewing.

Fig. 3
Fig. 3

Normalized current response as a function of time for varying intercontact lengths. The photon increase is a 10% ramp occurring over ∼10-9 s.

Fig. 4
Fig. 4

Normalized current response as a function of time for varying signal levels (1–600%). The photon increase is a ramp occurring over ∼10-6 s.

Fig. 5
Fig. 5

Composite plot, showing the effect of varying five parameters on the characteristic slow-component time constant. Parameters for the reference simulation are given in Table 2.

Fig. 6
Fig. 6

Fraction of the slow component as a function of photoconductive gain (μτE/ L). Points indicate simulations (sometimes multiple); the solid curve is a simple analytical model (not a best fit) for estimation purposes.

Fig. 7
Fig. 7

(a) Simulation for signal increase and decrease (Δg = 200%). (b) Same results with the decreasing signal inverted for comparison purposes.

Fig. 8
Fig. 8

Normalized current response as a function of time for a fixed signal level (Δg = 2 × 1011 cm-3) on decreasing background. The photon increase is a ramp occurring over ∼10-6 s.

Fig. 9
Fig. 9

Experimental current response as a function of time for two levels of background flux. The flux is decreased by using an additional neutral-density filter; the response is normalized for comparison.

Fig. 10
Fig. 10

Experimental current response as a function of time for three values of applied field (1.0, 2.0, and 2.5 V/cm). The response is normalized for comparison.

Fig. 11
Fig. 11

Experimental current response for a large-signal case, illustrating asymmetry in the transient behavior.

Tables (3)

Tables Icon

Table 1 Modeling Parameters for GaAs:Te (Figs. 1 and 2)

Tables Icon

Table 2 Modeling Parameters for GaAs:Te (Ref. Simulation)

Tables Icon

Table 3 Fraction of Slow Component

Equations (1)

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J=peμE+Ddp/dx+εdE/dt

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