Abstract

A photodiode made on high-resistivity silicon (greater than 100 Ω-cm) is characterized by a relatively wide junction-depletion layer. As a consequence, for most of the spectral response region the optical generation of charge carriers occurs within the depletion layer and the separation and collection of charge is primarily controlled by electric field rather than by diffusion. Short collection times thus obtained are estimated to be in the range from 10 to 100 nsec and have been shown to be 200 nsec or less. By choice of sufficiently high resistivity and moderate reverse biases the device capacitance can be kept smaller than circuit stray capacitances.

Low values of saturation current have been obtained resulting in high diode sensitivities. Best measured noise-equivalent-power values of 2×10−13 W at 0.9 μ are about a factor 2 short of theoretical values.

© 1962 Optical Society of America

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References

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  1. J. J. Loferski and J. J. Wysocki, RCA Rev. 22, 38–56 (1961).
  2. E. S. Rittner, “Electron Processes in Photoconductors,” Photoconductivity Conference, edited by R. G. Breckenridge (John Wiley & Sons, Inc., New York, 1956), p. 245.
  3. R. L. Williams and P. P. Webb, RCA Rev. 23, 29–46 (1962).
  4. A. Van der Zeil, Noise in Electron Devices, edited by L. D. Smullin and H. A. Haus (Technology Press, Massachusetts Institute of Technology, Cambridge, Massachusetts, and John Wiley & Sons, Inc., New York, 1959), Chap. 6.
  5. W. C. Dash and R. Newman, Phys. Rev. 99, 1151–1155 (1955).
    [Crossref]
  6. H. R. Phillip and E. A. Taft, Phys. Rev. 120, 37–38 (1960).
    [Crossref]
  7. W. W. Gärtner, Phys. Rev. 116, 84 (1956).
    [Crossref]
  8. P. P. Webb, R. L. Williams, and R. W. Jackson, “An Encapsulated Silicon Junction Alpha Particle Detector,” IRE Trans. on Nuclear Sci. NS-7, 199 (1960).
    [Crossref]

1962 (1)

R. L. Williams and P. P. Webb, RCA Rev. 23, 29–46 (1962).

1961 (1)

J. J. Loferski and J. J. Wysocki, RCA Rev. 22, 38–56 (1961).

1960 (2)

P. P. Webb, R. L. Williams, and R. W. Jackson, “An Encapsulated Silicon Junction Alpha Particle Detector,” IRE Trans. on Nuclear Sci. NS-7, 199 (1960).
[Crossref]

H. R. Phillip and E. A. Taft, Phys. Rev. 120, 37–38 (1960).
[Crossref]

1956 (1)

W. W. Gärtner, Phys. Rev. 116, 84 (1956).
[Crossref]

1955 (1)

W. C. Dash and R. Newman, Phys. Rev. 99, 1151–1155 (1955).
[Crossref]

Dash, W. C.

W. C. Dash and R. Newman, Phys. Rev. 99, 1151–1155 (1955).
[Crossref]

Gärtner, W. W.

W. W. Gärtner, Phys. Rev. 116, 84 (1956).
[Crossref]

Jackson, R. W.

P. P. Webb, R. L. Williams, and R. W. Jackson, “An Encapsulated Silicon Junction Alpha Particle Detector,” IRE Trans. on Nuclear Sci. NS-7, 199 (1960).
[Crossref]

Loferski, J. J.

J. J. Loferski and J. J. Wysocki, RCA Rev. 22, 38–56 (1961).

Newman, R.

W. C. Dash and R. Newman, Phys. Rev. 99, 1151–1155 (1955).
[Crossref]

Phillip, H. R.

H. R. Phillip and E. A. Taft, Phys. Rev. 120, 37–38 (1960).
[Crossref]

Rittner, E. S.

E. S. Rittner, “Electron Processes in Photoconductors,” Photoconductivity Conference, edited by R. G. Breckenridge (John Wiley & Sons, Inc., New York, 1956), p. 245.

Taft, E. A.

H. R. Phillip and E. A. Taft, Phys. Rev. 120, 37–38 (1960).
[Crossref]

Van der Zeil, A.

A. Van der Zeil, Noise in Electron Devices, edited by L. D. Smullin and H. A. Haus (Technology Press, Massachusetts Institute of Technology, Cambridge, Massachusetts, and John Wiley & Sons, Inc., New York, 1959), Chap. 6.

Webb, P. P.

R. L. Williams and P. P. Webb, RCA Rev. 23, 29–46 (1962).

P. P. Webb, R. L. Williams, and R. W. Jackson, “An Encapsulated Silicon Junction Alpha Particle Detector,” IRE Trans. on Nuclear Sci. NS-7, 199 (1960).
[Crossref]

Williams, R. L.

R. L. Williams and P. P. Webb, RCA Rev. 23, 29–46 (1962).

P. P. Webb, R. L. Williams, and R. W. Jackson, “An Encapsulated Silicon Junction Alpha Particle Detector,” IRE Trans. on Nuclear Sci. NS-7, 199 (1960).
[Crossref]

Wysocki, J. J.

J. J. Loferski and J. J. Wysocki, RCA Rev. 22, 38–56 (1961).

IRE Trans. on Nuclear Sci. (1)

P. P. Webb, R. L. Williams, and R. W. Jackson, “An Encapsulated Silicon Junction Alpha Particle Detector,” IRE Trans. on Nuclear Sci. NS-7, 199 (1960).
[Crossref]

Phys. Rev. (3)

W. C. Dash and R. Newman, Phys. Rev. 99, 1151–1155 (1955).
[Crossref]

H. R. Phillip and E. A. Taft, Phys. Rev. 120, 37–38 (1960).
[Crossref]

W. W. Gärtner, Phys. Rev. 116, 84 (1956).
[Crossref]

RCA Rev. (2)

J. J. Loferski and J. J. Wysocki, RCA Rev. 22, 38–56 (1961).

R. L. Williams and P. P. Webb, RCA Rev. 23, 29–46 (1962).

Other (2)

A. Van der Zeil, Noise in Electron Devices, edited by L. D. Smullin and H. A. Haus (Technology Press, Massachusetts Institute of Technology, Cambridge, Massachusetts, and John Wiley & Sons, Inc., New York, 1959), Chap. 6.

E. S. Rittner, “Electron Processes in Photoconductors,” Photoconductivity Conference, edited by R. G. Breckenridge (John Wiley & Sons, Inc., New York, 1956), p. 245.

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Figures (9)

Fig. 1
Fig. 1

Comparison of a solar cell (in which optically freed electron-hole pairs diffuse to junction to produce photocurrent) to a high-resistivity diode (in which optically freed electron-hole pairs are separated by the electric field of the depletion layer). The depletion layer of the high-resistivity diode is sufficiently wide that optical absorption takes place primarily in the field region. The charge-collection process is then essentially a field rather than a diffusion process.

Fig. 2
Fig. 2

(a) Schematic diagram of a high-resistivity diode and associated circuit. (b) The equivalent circuit of the diode.

Fig. 3
Fig. 3

Forward and reverse current-voltage characteristic of a diode. Although the reverse current is not an ideal saturation current, the forward current follows the ideal curve I=I0[exp×(qV/kT)−1]. By extrapolation of the forward current to 0 V I0 can be determined.

Fig. 4
Fig. 4

The measured quantum spectral response. The charge collected per quantum is compared to the ideal or reflection-only curve (1–R). Different short-wavelength responses are obtained for the different surface diffusions.

Fig. 5
Fig. 5

Insensitivity of the long-wavelength response to variations of the depletion-layer width. The response is theoretically predicted to increase by a factor of 30 as the depletion layer widens to 1 mm at 400 V. The wavelength used for this test was 1.1 μ for which the absorption coefficient is equal to 8 cm−1.

Fig. 6
Fig. 6

Measured values of the best D* values obtained for 5 mm2 diodes made from 3000 Ω-cm silicon. The diodes were operated in the photovoltaic mode.

Fig. 7
Fig. 7

Average NEP values obtained for devices of different areas. To be appropriate to D* notation, the NEP points should fall on a curve of slope of 1 2.

Fig. 8
Fig. 8

A reverse-biased diode has a sufficiently high impedance that the load resistor determines the signal and noise voltages. In the diagram the increase of responsivity and noise at low biases occurs as the diode resistance becomes greater than the load resistance. Discussions of noise and D* variations are given in the text.

Fig. 9
Fig. 9

A wide range of linearity—10 decades—can be obtained by biasing a unit. The extreme range of linearity that can be obtained is determined by the device noise and the breakdown voltage of the diode.

Tables (3)

Tables Icon

Table I Comparison of the measured photovoltaic junction impedance to that calculated from measured values of I0.

Tables Icon

Table II Sensitivity data.a

Tables Icon

Table III Speed of response to alpha particles at 3-V reverse bias—capacitance and resistivity values.

Equations (20)

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I ϕ = η ϕ q A .
V 0 = I ϕ R L R c + R L [ 1 R j + 1 R c + R L ] - 1 .
V 0 = I ϕ [ R L R j / ( R j + R L ) ] .
V 0 = I ϕ R L .
V 0 = I ϕ R j 0 .
I j = I 0 [ exp ( q V / k T ) - 1 ] ,
R j 0 = k T / q I 0 .
I j = I 0 [ exp ( q V 0 / k T ) - 1 ] = I ϕ ,
V 0 = ( k T / q ) ln ( 1 + I ϕ / I 0 ) ,
V 0 ( f ) = I ϕ R e ( 1 + ω 2 R e 2 C d 2 ) - 1 ,
C d = A [ q N a / 8 π ( V d + V ) ] 1 2 = A [ / 8 π μ p ρ ( V D + V ) ] 1 2 .
τ 0.1 - 0.9 = 1.07 × 10 - 12 ρ sec .
i n 2 = 2 q I j Δ f .
V n = i n [ R L R j / ( R L + R j ) ] .
V n = ( 2 q I 0 Δ f ) 1 2 R L .
V n 0 = ( 4 q I 0 Δ f ) 1 2 R j 0 ,
V n 0 = ( 4 k T R j 0 Δ f ) 1 2 .
s / n = I ϕ / ( 2 q I 0 Δ f ) 1 2 .
s / n 0 = I ϕ / ( 4 q I 0 Δ f ) 1 2 = I ϕ / ( 4 k T Δ f / R j 0 ) 1 2 .
NEP = [ 4 k T Δ f / R j 0 ] 1 2 ( 1 / Responsivity ) .