QE versus temperature

[Hopkinson, Gordon]

Posted to CCD-world:
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Hello CCD world

I've recently checked out the QE versus temperature effect and basically
agree with Andor's curves at long wavelengths.  The effect is due to the
change in absorption length as you approach the cut-off at 1.1 microns.

I have used the expression : a(l) = [(84.732/l) - 76.417] from [1] (a in
cm-1, l in mm), and an expression for the temperature shift from [2].

[1]   E. S. Nartowitz and A. M. Goodman, " Evaluation of silicon optical
absorption data for use in minority-carrier-diffusion-length measurements by
the SPV method", J. Electrochem. Soc., vol. 132(12), pp 2992-2997 (1985)

[2]    H. A. Weakliem and D. Redfield, "Temperature dependence of the
optical properties of silicon", J. Appl. Phys. Vol. 50 (3), pp1491-1493
(1979)

To model the QE for a thinned CCD you need to take into account the multiple
reflections.

The effect at wavelengths below about 800nm may be due to changes in
reflection coefficient and some CCDs (particularly lumogen-coated) have
instabilities in the blue, but in general there shouldn't be much change
below 800nm so I don't know why Andor  show the large changes at low
wavelengths.

Best regards

Gordon Hopkinson
Sira Electro-Optics Ltd

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