Silicon Drift Detector Linear Anodes for Count Rate
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Solution Overview
Problem
Large area silicon solid state detectors face limitations such as ballistic deficit, which causes electron spread and reduces count rate performance, and existing solutions like small area pin pixel devices require specialized interconnects and do not meet resolution requirements for radiation detection applications.
Innovation Solution
The development of large area silicon drift detectors with linear anodes and oblong-shaped steering electrodes, along with specific biasing configurations and geometries, such as periodic arrays of rectangular anodes and inter-digitized structures, to reduce drift distances and capacitance, thereby improving count rate performance and resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If large area SDD detectors are used to increase detection area, then detection area is improved, but ballistic deficit increases causing electron spread and reduced count rate performance
Solution Approach 1:
The detector is divided into multiple independent pixel elements, each with its own readout electronics. This segmentation allows each pixel to operate independently with optimized drift distances, reducing ballistic deficit while maintaining large total detection area through the array configuration.
Solution Approach 2:
The patent transitions from traditional planar electrode configurations to a three-dimensional pixel structure with vertical drift paths. By utilizing the vertical dimension for electron drift toward the anode, the detector achieves shorter effective drift distances within each pixel while maintaining large horizontal detection area.
2Productivity
If small area pin pixel devices are used to improve count rate performance, then count rate performance is improved, but resolution requirements for radiation detection applications are not met
Solution Approach 1:
The patent combines the advantages of small pixel devices (short drift distances, high count rate) with large area detectors by creating an array of pixels that are electrically and physically connected to share readout electronics. This merging allows the system to achieve both high count rate performance and sufficient resolution for radiation detection.
Solution Approach 2:
The pixel detector design serves multiple functions: it provides high count rate performance through short drift distances, achieves sufficient resolution through appropriate pixel sizing and positioning, and enables large area detection through the array configuration. This multi-functional design resolves the contradiction between count rate and resolution.
3Quantity of substance
If conventional circular anode SDDs are used, then detector capacitance is reduced, but drift distance is increased causing ballistic deficit
Solution Approach 1:
The patent employs asymmetric pixel geometries where the anode structure and electrode positioning are optimized to create non-uniform electric fields that shorten the effective drift path. The asymmetric design allows electrons to be funneled toward collection points more efficiently, reducing drift distance while maintaining low capacitance through the pixel structure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
These designs achieve shorter electron drift distances, lower shaping times, and enhanced count rate performance while maintaining or improving resolution, making them suitable for direct detection of ionizing radiations like alphas, betas, and X-rays.
Implementation Method 1
free electrons generated from the radiation absorption within the material to repel each other as they drift towards the anode
Implementation Method 2
radiation absorption within the material
Implementation Method 3
concentric drift electrodes around an anode on the counter irradiation side and a continuous p+ junction on the irradiation side
Implementation Method 4
biasing configurations wherein the irradiation and anode stop rings (edge electrodes) are set at the same reverse bias
Data Source
AI summary
A large area SDD detector having linear anodes surrounded by steering electrodes and having an oblong, circular, hexagonal, or rectangular shape. The detectors feature stop rings having a junction on the irradiation side and an ohmic contact on the anode side and/or irradiation side. The irradiation and anode stop ring biasing configuration influences the leakage current flowing to the anode and, hence, the overall efficiency of the active area of the detector. A gettering process is also described for creation of the disclosed SDD detectors. The SDD detector may utilize a segmented configuration having multiple anode segments and kick electrodes for reduction of the detector's surface electric field. In another embodiment, a number of strip-like anodes are linked together to form an interdigitated SDD detector for use with neutron detection. Further described is a wraparound structure for use with Ge detectors to minimize capacitance.