Radiation Detector Electrode Layout for Edge Carrier Loss
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Solution Overview
Problem
The carrier transport property decreases in the end portion of semiconductor substrates used in radiation detectors due to machining defects, leading to reduced signal strength and deteriorated image quality.
Innovation Solution
The arrangement of pixels with varying electrode sizes on the semiconductor substrate, where electrodes in the outer edge pixels are smaller than those closer to the center, along with capacitors and amplifiers connected to each electrode, to enhance electron collection and suppress the influence of decreased carrier transport property.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrodes are arranged in the end portion of the semiconductor substrate, then charge collection is enabled, but carrier transport property decreases due to machining defects
Solution Approach 1:
The patent applies different electrode configurations to different regions of the semiconductor substrate. Specifically, pixels in the end portion (first pixels) use multiple smaller electrodes, while pixels in the central portion (second pixels) use a single larger electrode. This local differentiation addresses the carrier transport property degradation in the end portion by optimizing the electrode structure to reduce sensitivity to machining defects in that specific region.
2Reliability
If multiple small electrodes are used in end portion pixels, then influence of carrier transport decrease is reduced, but device complexity increases
Solution Approach 1:
The patent segments the electrode structure in the end portion pixels by dividing each pixel into multiple smaller electrodes instead of using a single large electrode. This segmentation reduces the impact of carrier transport property degradation caused by machining defects in the end portion, as the smaller electrodes have reduced sensitivity to edge effects and defects.
3Measurement precision
If electrode area is increased to improve signal strength, then charge collection efficiency improves, but spreading of electric field increases causing image quality deterioration
Solution Approach 1:
The patent implements different electrode area configurations for different spatial regions. Pixels in the end portion use multiple smaller electrodes with reduced individual area, while pixels in the central portion use larger electrodes. This local quality differentiation ensures that where electric field spreading would most adversely affect image quality (the end portions), the electrode configuration is optimized to minimize such spreading, while maintaining adequate signal strength through the multi-electrode arrangement.
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 configuration maintains sufficient signal strength and improves image quality by reducing the contribution of holes to the signal, thereby mitigating the impact of decreased carrier transport in the end portion of the semiconductor substrate.
Implementation Method 1
a semiconductor substrate configured to convert incident radiation into charges
Implementation Method 2
a plurality of capacitors configured to accumulate signals generated by the plurality of pixels
Data Source
AI summary
A radiation detector obtained by arranging a plurality of pixels on a semiconductor substrate configured to convert incident radiation into charges is provided. The plurality of pixels comprise a first pixel arranged along an outer edge of the semiconductor substrate and a second pixel arranged closer to a center of the semiconductor substrate than the first pixel. The first pixel comprises a plurality of first electrodes on a principal surface of the semiconductor substrate, the second pixel comprises a second electrode on the principal surface, and an area of the second electrode is larger than an area of each of the plurality of first electrodes. A plurality of capacitors configured to accumulate signals generated by the plurality of pixels are further comprised so that one capacitor is connected in correspondence with each of the plurality of first electrodes and the second electrode.