Effect of Anode Floating Voltage and its Applications in Characterizing Silicon Drift Detectors

Anode floating voltage is predicted and investigated for silicon drift detectors (SDDs) with an active area of 5mm² fabricated by a double-side parallel technology. It is demonstrated that the anode floating voltage increases with the increasing inner ring voltage, and is almost unchanged with the external ring voltage. The anode floating voltage will not be affected by the back electrode biased voltage until it reaches the full-depleted voltage (-50V) of the SDD. Theoretical analysis and experimental results show that the anode floating voltage is equal to the sum of the inner ring voltage and the built-in potential between the p⁺ inner ring and the n⁺ anode. A fast checking method before detector encapsulation is proposed by employing the anode floating voltage along with checking the leakage current, potential distribution and drift properties.