SDD 工作原理和主要特点
The working principle of the Silicon Drift Detector (SDD)
The working principle of the Silicon Drift Detector (SDD) is based on the concept of sideward depletion invented by Pavel Rehak and Emilio Gatti in 1983 [1]. It allows the depletion of a large volume of high-resistivity silicon material by a small anode receiving a minimum signal capacitance. By that, the SDD overcomes the major problem of a classical p-i-n diode detector where the input capacitance is direct proportional to the active area. Figure 1 shows a schematic view of the SDD in its standard configuration [2]:
While the back contact is made up by a homogeneous, shallow p+n junction on the side where the incoming radiation enters the detector, the opposite side is characterized by a structure of circular p+ drift rings and eventually an integrated first FET for on-chip amplification. By applying a negative voltage on the radiation entrance window and an increasingly negative voltage on the drift rings, a potential field distribution is created such that the electrons generated by the ionizing radiation drift towards the small sized collecting anode situated in the center of the device. In the case of an integrated FET, the signal is directly amplified without adding any additional noise or microphony problems by bond wires.
[1] Rehak, P., Gatti, E. (1985) et al.: Nucl. Instr. & Meth. A235 (1985), 224-234
[2] Lutz, G. (1999): “Semiconductor Radiation Detectors”, 237
[Translate to Chinese:] Fig. 1 Schematic 3D view of a round silicon drift detector
Key Features
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Best energy resolution down to 121 eV @ Mn-Kα, – 30°C
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Polysilicon technology for ultra-low leakage current values < 100 pA/cm², enabling high performance spectroscopy close to room temperature
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pnWindow for the best light element detection and optimum P/B ratio up to 20 000
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Wide selection of chip sizes and detector housings 5, 10, 20, 30, 60, 80, 100, 200, 300, 600 mm²
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Unique shapes like our Rococo Series and the Rococo Detectors
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High count rates up to 1 Mcps with single cells and several Mcps with our monolithic Multi-Element SDDs
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Radiation hardness >1014 Photons/cm²
