Photon Counting Detector With Segmented Steering Electrodes
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Solution Overview
Problem
Existing X-ray photon counting detectors face challenges in achieving fast counting performance due to the degradation effect of charge sharing, where reducing pixel size enhances pulse sharpening but increases the likelihood of charge loss, leading to incomplete energy information.
Innovation Solution
The use of a spatially modulated doping profile within the semiconductor detector, combined with steering electrodes on the same potential as the collecting anodes, modifies the electric field to guide charges effectively without the need for high voltage on the steering electrode, thereby reducing offset currents and technological complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If pixel size is reduced to enhance pulse sharpening, then pulse width is reduced and counting speed is improved, but charge sharing increases and energy resolution deteriorates
Solution Approach 1:
The detector is divided into collecting electrodes and steering electrodes with distinct functions. The steering electrodes are further segmented into multiple regions with different doping profiles, allowing independent optimization of charge collection and pulse sharpening functions without compromising energy resolution.
Solution Approach 2:
Different regions of the steering electrode are doped with different doping concentrations and types (n-type or p-type) to create localized electric field modifications. This allows the steering electrode to provide pulse sharpening in specific areas while maintaining proper charge collection in other areas, resolving the contradiction between speed and energy resolution.
2Reliability
If steering electrode potential is increased to guide charges effectively, then charge collection efficiency is improved, but offset currents increase and device complexity increases
Solution Approach 1:
The steering electrode is configured to be at the same electrical potential as the collecting electrode, eliminating potential differences that would cause offset currents. This equipotential configuration simplifies the electrical system while maintaining effective charge guidance through the spatially modulated doping profile that creates localized field modifications.
Solution Approach 2:
The patent replaces the traditional approach of using high voltage electrical fields for charge guidance with a doping profile-based electric field modification. The spatially varying doping concentration creates the necessary field gradients passively, eliminating the need for complex high voltage steering electrode configurations.
3Measurement precision
If pixel pitch is maintained to avoid charge sharing, then energy resolution is preserved, but pulse sharpening is reduced and counting speed decreases
Solution Approach 1:
The steering electrode with spatially modulated doping acts as an intermediary element between the collecting electrode and the charge carriers. It provides the necessary field modification for pulse sharpening without requiring reduced pixel pitch, thus maintaining both energy resolution and counting speed independently.
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
This approach enhances pulse sharpening while maintaining pixel pitch, reducing charge sharing and improving energy resolution without the need for high voltage application, thus enhancing the detector's ability to accurately measure photon energies.
Implementation Method 1
modifies the electric field to guide charges effectively
Implementation Method 2
the electric field within the semiconductor is bended such that the charges are guided essentially towards the collecting electrodes
Implementation Method 3
An incident photon creates a number of electron/hole pairs
Implementation Method 4
The charges are separated in the electric field, i.e., electrons are drifting towards an (eventually segmented) anode, and holes are drifting towards an (eventually segmented) cathode
Data Source
AI summary
A radiation detector (10) includes a semiconductor element (1) for generating positive holes and electrons, a cathode (2) formed on a first surface of the semiconductor element (1) and a plurality of segmented anodes (3) formed on a second surface of the semiconductor element (1), the second surface being in opposed relation to the first surface. Additionally, a plurality of segmented steering electrodes (5a) are positioned adjacent the plurality of segmented anodes (3). Moreover, a plurality of doping atoms are located above at least a portion of the plurality of segmented anodes (3) for reducing the voltage difference between the plurality of segmented anodes (3) and the plurality of segmented steering electrodes (5a).