CdTe Sensors

The PILATUS3 X CdTe detector series uses cadmium telluride (CdTe) crystals as the sensor material for direct conversion of the hard X-ray radiation. This high-Z semiconductor material (Cd with Z=48, Te with Z=52) provides excellent stopping power, resulting in superior detection efficiency even at high X-ray energies.

DECTRIS employs CdTe sensors material from the leading manufacturer in some of the largest sizes available today. Each PILATUS3 CdTe detector module is built from two large CdTe sensors (42 mm × 34 mm), leaving a horizontal gap of only one pixel between the two crystals. The CdTe thickness of 1000 µm provides high quantum efficiency for hard X-ray energies up to 100 keV. 

Figure 1 and Table 1 show the quantum efficiency (QE) for the 1000 µm CdTe sensors as a function of energy. The QE values were simulated for the PILATUS3 pixel size and geometry, and measured in the PTB laboratory at BESSY II from 20 keV to 60 keV. The measurements confirm the values predicted by simulation.

Figure 1: Quantum efficiency of the PILATUS3 X CdTe detector module measured in cooperation with PTB
at the BAM beamline at BESSY II. The dip in the QE from above 26 keV is caused by fluorescence losses
 occurring for photon energies above the Cd and Te K-edges. The QE is measured for energy threshold set to
50% of the photon energy.

Photon energy CdTe 1000 µm
20.0 keV > 90%
40.0 keV 81%
60.0 keV 90%
80.0 keV 77%
100.0 keV 56%

Table 1: Quantum efficiency of PILATUS3 CdTe sensors.