Pixel Volume Confinement in Energy Resolving X-ray Detectors
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Solution Overview
Problem
Energy resolving detectors in Computed Tomography face challenges in maintaining high count rate capability and spectral information resolution due to charge sharing across pixels, which degrades energy estimation and location accuracy, and existing methods to address this often result in defects or reduced performance.
Innovation Solution
The method involves inducing a break line in the crystal along pixel virtual limits using a focused ion beam or ion implantation, followed by passivation to prevent charge trapping and confinement of electrons within pixels, thereby minimizing charge sharing. This is achieved by creating submicron gaps using FIB or introducing an oxide to form an oxidized region, and optionally doping the anode side with Indium to strengthen the electric field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pixel size is reduced to increase count rate capability, then count rate per unit area is improved, but energy resolution deteriorates due to charge sharing across pixels
Solution Approach 1:
The crystal is segmented into pixels by inducing break lines along pixel virtual limits, creating physical boundaries that prevent charge sharing between adjacent pixels while maintaining small pixel sizes for high count rate capability
Solution Approach 2:
The break lines are selectively induced only at pixel boundaries rather than throughout the entire crystal, creating localized confinement structures that prevent charge sharing without affecting the overall pixel volume and energy resolution
2Measurement precision
If break line is induced to prevent charge sharing, then charge sharing is reduced, but charge trapping occurs at the break line location
Solution Approach 1:
An intermediary material or process (passivation layer or oxidized region) is introduced at the break line to eliminate charge trapping sites while maintaining the physical boundary function, thus preserving both charge sharing prevention and charge collection efficiency
Solution Approach 2:
The break line, which initially creates charge trapping sites, is transformed into a beneficial structure through passivation that prevents charge sharing while eliminating the harmful trapping effect, converting a potential defect into a functional boundary
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 effectively confines electrons within pixels, reducing charge sharing and enhancing charge collection efficiency while maintaining high resolution and minimizing pixel volume loss, thus improving the accuracy of energy estimation and location precision in energy resolving detectors.
Implementation Method 1
inducing a break line in the crystal along pixel virtual limits wherein the break line is induced by at least one of a focused ion beam and ion implantation
Implementation Method 2
passivating the break line
Data Source
AI summary
Method of pixel volume confinement in a crystal of an energy resolving radiation detector, preferably an X-ray detector, more preferably a Computed Tomography detector, the crystal having a cathode side and an anode side, comprising: a. Inducing a break line (501) in the crystal along a pixel virtual limits b. Passivating the break line.