Gy. Prigozhin et al., X-RAY-ABSORPTION NEAR-EDGE STRUCTURE IN THE QUANTUM EFFICIENCY OF X-RAY CHARGE-COUPLED-DEVICES, Optical engineering, 37(10), 1998, pp. 2848-2854
We perform precise measurements of the x-ray transmission of the thin
films comprising CCD gate structure, namely, phosphorus doped polysili
con, silicon dioxide, and silicon nitride. The x-ray transmission of t
hese films shows large oscillations with small changes in energy in th
e vicinity of the following absorption edges: nitrogen K (400 eV), oxy
gen K (536 eV), silicon L and K (100 and 1840 eV, respectively). As a
result, quantum efficiency of a CCD in the soft x-ray range deviates s
ignificantly from simple model predictions based on Henke et at. (1993
) mass absorption coefficients. The measurements covered the range of
energies from 60 to 3000 eV, using synchrotron beamlines at the Advanc
ed Light Source (ALS; Berkeley), Physikalisch-Technische Bundesanstalt
BESSY (Berlin), the Synchrotron Radiation Center (SRC; University of
Wisconsin-Madison). Our model of the CCD response includes near edge x
-ray absorption structure and predicts a very complicated shape of the
energy dependence of the quantum efficiency around silicon and oxygen
absorption edges. Experimental measurements of CCD quantum efficiency
relative to a calibrated detector at the BESSY synchrotron confirmed
our model predictions for both frontside and backside illuminated CCDs
. (C) 1998 Society of Photo-Optical instrumentation Engineers. [S0091-
3286(98)01910-2].