243 17
Gold Layer, Aluminum Layer, Nickel Layer
Detector crystals typically have conductive layers on their
front face to ensure conductivity. These layers can be con-
structed by depositing various different metals on the sur-
face. The absorption profiles of these layers will decrease the
efficiency of the detector. The layer thicknesses are particu-
larly relevant for simulation; however, other uncertainties
usually exceed the effect of the conductive layer.
Dead Layer
The dead layer is an inactive or partially active layer of silicon
on the front face of the detector. The dead layer will absorb
some X-rays (particularly low energy X-rays) and produce
few to no electron–hole pairs. The result is a fraction of X-rays
which produce no signal or a smaller signal than their energy
would suggest. The result is twofold: The first effect is a dimin-
ishment of the number of low energy X-rays detected. The
5 000
10 000
15 000
20 000
25 000
30 000
35 000
0
Counts
5 600 5 700 5 800 5 900 6 000 6 100 6 200
Energy (eV)
Mn 1
Full height
Mn
K-L3
Mn
K-L2
. Fig. 17.5 Estimating the full width at half-maximum peak width. This peak is approximately 139 eV FWHM which you can confirm with a ruler
WD: Working distance
DD: Detector distance
Side view
Electron
column
X
X
Z
Y
Y
Sample
Elevation
Detector snout
DD
WD
Electron
column
Top view
looking down
Detector
Ele
column
Detector
Ele
Detector
Azimuth
. Fig. 17.6 Definitions of elevation angle and azimuthal angle
17.1 · Getting Started With NIST DTSA-II