Comparison of Various X-ray Spectrometers
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Table 2527. Comparison of various X-ray spectrometers.

Model
Si(Li) detector
Si-drift detectors
(SDDs)
Intrinsic-Ge (IG) detector
Wavelength dispersive X-ray spectroscopy (WDXRF/WDS)
Bolometer
Characteristics
 Energy dispersive

Crystal diffraction

  
Major advantages
More sensitive to high-energy x-rays than SDD detector
Extremely high-count rates with good resolution and peak stability
High energy X rays such as gold Kα (69 keV)
High energy resolution
Disadvantages

K-shell absorption edge at 11.1 keV; Complex L-shell absorption edge structure starting at 1.4 keV; A series of escape peaks in the range 2-12 keV
Slow data acquisition due to smaller solid angle than that in EDS
Artifacts
Sum peaks Si K peak
Sum peaks Si K peak; less sensitive to high-energy x-rays than Si(Li) detector
Sum peaks Ge K/L peaks
High-order lines
FWHM energy resolution (eV)
Energy dependent
Crystal dependent: 5 - 10
 
128 - 150: degrades substantially with increased input count rate due to slow response of diode geometry
125 - 155: degrades slowly with increasing count rate due to fast response of radial field geometry; decreasing the device temperature makes the resolution better
114 - 135
5 - 10
Typical output rates (Kcps)
Medium: 5 – 20
1000 to >100 kcps per channel
5 – 10
50
1
Sensitivity
 0.1-1%
0.01 - 0.1%
Good sensitivity from ~70 eV (Be-K) to ~20 keV; reduced sensitivity until 50 keV
Good sensitivity up to 10 keV; reduced sensitivity until 20 keV
Quantum efficiency
~100% for 2-16 keV Variable, <30%  
Elements detected
 Z ≥ 11 (Na) for Be window； Z ≥ 6 (C) for windowless Z ≥ 5 (B)  
Typical time to collect full spectrum
~ 1 min
0.25 μs ~ few secs
~ 1 min
~ 30 min to hours
~ 30
Pixel dwell times
≥ A few μs
Energy to form electron-hole pairs at 77 K (eV)
3.8
3.8
2.9
N.A.
N.A.
Indirect band gap energy (eV)
1.1
1.1
0.67
N.A.
N.A.
Operating Temperature
Extreme cooling required to reduce electronic noise (77~130 K): LN2, thermoelectric, or Peltier+water or refrigeration
230~250 K: Peltier cooling, thermoelectric, or no cooling (most have convective cooling, some have fans (vibration))
LN2 or thermoelectric
None
100 mK
Detector active area (mm2)
4 to >50
≥ 50 to 120 [1]
10 to >50
N.A.
1
Collection angle (sr)
0.03 – 0.3
0.3
0.03 – 0.2
10–4–10–3
10–4–10–3
Take-off angle (°)
0, 20, 72
20
0, 20, 72
40 – 60
40 – 60
Sensor thickness
E.g. 3 mm
0.5 mm
Availability of detector arrays
No
Yes
No
No
Yes
Electric Field & electron Path
Axial field
Radial field
Electrical contact
Small
Total noise
Low
1/f noise
Dominates at high shaping times
Capacitance
High: The total capacitance in Si(Li) detectors is much higher than that in SDD detectors.
Low: The total capacitance in SDD detector is much lower than that in Si(Li) detector.
Leakage current
The leakage current in Si(Li) detectors is much lower than that in SDD detectors.
The leakage current in SDD detectors is much higher than that in Si(Li) detectors.
Fabrication Technology
 Discrete components Semiconductor; Size and shape limited only by fabrication technology      
Application frequency
Less frequent
Less frequent

 

 

[1] H.S. von Harrach, P. Dona, B. Freitag, H. Soltau, A. Niculae, M. Rohde, An integrated Silicon Drift Detector System for FEI Schottky Field Emission Transmission Electron Microscopes, Microsc Microanal 15(Suppl 2), 2009 (208).

 

 

 
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