Semiconductor Pellet Manufacturing for X-ray Detectors
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Solution Overview
Problem
Current methods for manufacturing semiconductor materials for direct conversion X-ray detectors face challenges such as high costs, health hazards, porosity issues, and difficulty in achieving large-scale production with uniform surface conditions and controlled stoichiometry, leading to suboptimal detector performance and safety concerns.
Innovation Solution
A method involving the use of a semi-polycrystalline powder of PbI2, HgI2, and/or PbO, subjected to axial compression and controlled heating to produce a semiconductor pellet with high purity and preferential grain orientation, enhancing electrical conversion efficiency and reducing porosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods are used to manufacture semiconductor materials for direct conversion X-ray detectors, then production costs are reduced and manufacturing is simplified, but the materials exhibit high porosity, poor electrical transport properties, and suboptimal detector performance
Solution Approach 1:
The invention changes the physical-chemical parameters of the manufacturing process by applying high pressure (1-10 GPa) and elevated temperature (200-1000°C) simultaneously to the semiconductor powder. This parameter combination transforms the material structure to achieve high density and low porosity while maintaining manufacturing feasibility, resolving the contradiction between detector performance and ease of manufacture
Solution Approach 2:
The invention uses composite powder compositions containing multiple semiconductor materials (e.g., HgI2, PbI2, CdTe) with specific particle size distributions and morphologies. This composite approach optimizes both the electrical transport properties for high detector performance and the packing efficiency for easier manufacturing with reduced porosity
2Measurement precision
If high purity semiconductor powder is used, then detector sensitivity is improved, but production costs increase and manufacturing becomes more complex
Solution Approach 1:
The invention performs preliminary purification and characterization of the semiconductor powder before the high-pressure high-temperature treatment. This preliminary action ensures adequate purity levels are achieved through standard purification methods, avoiding the need for excessively high purity materials while still achieving high detector sensitivity after the HPHT processing enhances the material properties
3Productivity
If rapid image acquisition is implemented for panoramic radiographs, then productivity is improved, but the detector must detect quickly which requires optimized material properties
Solution Approach 1:
The invention changes the electrical parameters of the semiconductor material by applying high pressure and temperature, which enhances charge carrier mobility and reduces recombination times. This enables the detector to rapidly respond to successive X-ray pulses required for panoramic radiography, achieving both high productivity and reliable fast detection capability
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 results in improved sensitivity, reduced porosity, and better electrical transport properties, enabling the production of high-performance direct conversion X-ray detectors with enhanced sensitivity and reduced production costs, while ensuring safety and scalability.
Implementation Method 1
a direct conversion detector directly transforms an incoming X-ray photon into electrical charges
Implementation Method 2
These charges are then collected by applying an electric field
Implementation Method 3
a step of heating said compacted powder for a specified time
Data Source
Figure 1~2b
Figure 3~4
AI summary
The present invention relates to a method for production of a pellet for a direct-conversion detector of X-rays. It also relates to a direct-conversion detector of X-rays using such a pellet and to a dental radiology apparatus using at least one such detector. The method for production of the pellet comprises a step of placing a powder of a semi-conductive polycrystalline material under a load (3, 4, 4a) and a step of heating (5-9) for a predetermined period of time. It comprises a prior step for bringing about an impurity level of at least 0.2% in the semi-conductive polycrystalline material.