Radiation Detector Grid Electrode for Charge Collection
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Solution Overview
Problem
Wide band-cap radiation detectors like CdTe and CdZnTe suffer from poor charge transport properties, particularly low hole mobility, leading to incomplete charge collection and depth-dependent signal variations, which degrade their performance in gamma-ray spectroscopy, and existing solutions like hemispherical structures, pulse-shape discrimination, and charge loss correction are either partially effective or limit detector efficiency.
Innovation Solution
A radiation detector with a grid electrode embedded within or between semiconductor layers acts as an electrostatic shield to block slow-moving carriers, allowing only fast-moving carriers to reach the collecting electrode, improving charge collection and enabling photon counting and integration for spectroscopy and imaging applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a grid contact is placed on the perimeter to assist charge collection, then charge collection is improved, but the field continuity cannot be guaranteed and detector efficiency is reduced for large detectors
Solution Approach 1:
The detector is divided into multiple segments with individual grid contacts placed at different locations (perimeter and internal positions) rather than relying on a single perimeter contact. This segmentation allows each region to have its own electrostatic shield, ensuring local field continuity while maintaining overall detector functionality for large-area detectors
Solution Approach 2:
The solution transitions from a two-dimensional perimeter-based grid contact arrangement to a three-dimensional configuration by placing grid contacts at multiple depths and positions within the detector volume. This includes internal grid contacts positioned between semiconductor layers or embedded within them, creating continuous electrostatic shielding throughout the detector volume rather than only at the perimeter
2Reliability
If hemispherical detector structures are used to address poor carrier mobility, then charge collection is partially improved, but the design is hard to realize for large-area pixilated two-dimensional architectures
Solution Approach 1:
The detector structure is segmented into planar semiconductor layers with discrete grid contacts at specific positions, avoiding the complex curved geometry of hemispherical detectors. This segmentation into flat, manufacturable layers with localized electrostatic shields maintains charge collection benefits while enabling standard semiconductor fabrication processes for large-area pixilated detectors
Solution Approach 2:
Instead of changing the overall detector geometry to hemispherical to improve charge collection, the invention inverts the approach by maintaining a planar detector structure and introducing internal electrostatic shielding elements. This reverses the conventional thinking of modifying external geometry and instead modifies the internal field structure, achieving improved charge collection while preserving ease of manufacture for large-area detectors
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
The solution enhances charge collection efficiency, reduces signal variations, and improves the signal-to-noise ratio, enabling more accurate readings and faster image acquisition, suitable for both photon counting and integration systems, including TFT and CMOS imagers.
Implementation Method 1
The grid layer can either be embedded within one of the semiconductor layers or located between a pair of semiconductor layers and acts as an electrostatic shield to block any slow moving carriers or oppositely charged carriers from collecting in, or on, the collecting electrode
Data Source
AI summary
The invention is directed at a radiation detector which includes a grid electrode located within the detector to assist in the charge collection process. The grid electrode is preferably embedded within a semiconductor layer between two electrode layers, one of the electrode layers being a charge collecting electrode and the other being a common electrode.