Design and Simulation of Silicon Drift Detector with Small Cathode Ring Spacing

硅漂移探测器(silicon drift detector, SDD)被广泛地用于X射线探测。本研究设计了小阴极环间距的SDD结构，使用Silvaco TCAD仿真软件分别对阴极环间距为10 μm和30 μm SDD进行了建模与仿真，对10 μm和30 μm阴极环间距SDD的电学特性进行了比较，对10 μm阴极环间距SDD的电容、瞬态阳极电流和电荷收集机制进行了分析。结果表明，相对于30 μm阴极环间距SDD，10 μm阴极环间距SDD有小的漏电流，平滑的电子漂移沟道，更大的横向漂移电场，均匀的电势分布，较低的电容，电荷收集时间约为100 ns。Silicon drift detector (SDD) is widely used for X-ray detection. This study designed an SDD structure with small cathode ring spacing, and modeled and simulated SDDs with cathode ring spacing of 10 μm and 30 μm using Silvaco TCAD simulation software. The electrical characteristics of SDDs with cathode ring spacing of 10 μm and 30 μm were compared, and the capacitance, transient anode current, and charge collection mechanism of SDDs with cathode ring spacing of 10 μm were analyzed. The results indicate that compared to the 30 μm cathode ring spacing SDD, the 10 μm cathode ring spacing SDD has smaller leakage current, smoother electron drift channel, larger lateral drift electric field, uniform potential distribution, lower capacitance, and charge collection time of about 100 ns.