PI0512WS Datasheet, PDF (3/8 Pages) AMI SEMICONDUCTOR – 512-Pixel 50-mm-Pitch Wide Aperture Spectroscopic Photodiode Array

During normal operation, the impinging photons in or near the PN photodiode junction
generate free charges that are collected and stored on the junction's depletion capacitance.
Since on average a certain fraction of charge is generated and collected for each impinging
photon, the number of collected charges will proportionally increase with light exposures.
Figure 3 shows the stored signal charge as function of light exposure at a wavelength of
575 nm. The exposure is the product of the light intensity in nW/cm² and integration time in
seconds. The charge accumulates linearly until reaching the saturation charge where the
corresponding exposure is the saturation exposure.
70
60
50
Saturation
40
Charge
30
20
Saturation
10
Exposure
0
0
50
100
150
200
Exposure (nJ/cm^2)
Figure 3. Stored signal charge as function of exposure at a wavelenogft5h75 nm.
The responsivity is defined as ratio of saturation charge divided by saturation exposure. The
measured typical responsivity of a photodiode is 3.3×10^-4 C/J/cm² at 575 nm. Figure 4 shows
the predicted responsivity of the photodiodes as a function of wavelength.
5.0E-04
4.5E-04
4.0E-04
3.5E-04
3.0E-04
2.5E-04
2.0E-04
1.5E-04
1.0E-04
5.0E-05
0.0E+00
100
QE=80%
QE=60%
QE=40%
QE=20%
300
500
700
900
Wavelength (nm)
Figure 4. Predicted spectral response.
PI0512WS Page 3 of 8 – July 26, 2001