Metal Mesh Upper Electrode for X-Ray Detector Matrix
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Solution Overview
Problem
The existing detection matrix devices face issues with high resistivity of the upper electrode and parasitic capacitances between the upper electrode and the control rows/columns, which affect the performance of organic photodetectors, particularly in large surface areas and during image acquisition in X-ray imagers.
Innovation Solution
A metallic mesh is formed next to the control rows and columns, with a dielectric layer of low relative permittivity (< 2.5) separating them, and the upper electrode is designed to have a metallic part and a dielectric part, reducing parasitic capacitances and increasing conductivity by exposing resin layers and etching to create studs, and using a self-assembled monolayer for direct contact without opening the detection layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the upper electrode is made transparent and contact is taken at peripheral points, then the detection resolution and transparency are improved, but the sheet resistance increases and conductivity decreases
Solution Approach 1:
The upper electrode is segmented into two distinct parts: a transparent portion for maintaining detection resolution and a metallic mesh portion for providing low-resistance electrical contact. This segmentation allows each part to fulfill its specific function optimally without compromising the other.
Solution Approach 2:
Different regions of the upper electrode are assigned different material properties: the central area uses transparent material for optimal light transmission, while the peripheral contact areas incorporate metallic mesh for low-resistance electrical connection. This local differentiation resolves the contradiction between transparency and conductivity.
2Reliability
If the upper electrode is made as a full plate, then the conductivity is improved, but parasitic capacitances between the upper electrode and control rows/columns increase
Solution Approach 1:
The upper electrode is segmented into a transparent portion and a metallic mesh portion positioned adjacent to control rows and columns. This segmentation reduces the overlapping area between the upper electrode and control lines, thereby minimizing parasitic capacitances while maintaining conductivity through the metallic mesh.
Solution Approach 2:
The metallic mesh is extracted and positioned separately adjacent to the control rows and columns rather than forming a continuous full plate. This extraction reduces the capacitive coupling between the upper electrode and control lines while the mesh structure maintains electrical conductivity.
3Reliability
If a dielectric layer with high permittivity is used to separate the metal mesh from control rows, then the insulation is improved, but the parasitic capacitances increase
Solution Approach 1:
The dielectric layer's permittivity parameter is optimized to a specific range that provides sufficient electrical insulation between the metal mesh and control rows while minimizing capacitive effects. By carefully selecting and controlling the dielectric constant, both insulation and low parasitic capacitance requirements are satisfied.
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 significantly reduces the sheet resistance of the upper electrode and minimizes parasitic capacitances, enhancing the detection matrix's performance by optimizing conductivity and transparency, thus improving image acquisition and detection resolution.
Implementation Method 1
using a self-assembled monolayer for direct contact without opening the detection layer
Implementation Method 2
a dewetting step comprises the grafting of a self-assembled monolayer (SAM - Self assembled monolayer) on the pads having at least one metal part in order to dewet the detection layer at this location
Data Source
Figure 1a~2
Figure 3a~3c
Figure 3d~3f
AI summary
The present invention relates to a matrix detection device comprising a stack including a matrix of detection element pixels, an active matrix including a network (20) of rows and columns for controlling said pixels, which is produced on the surface of a substrate (10), characterised in that: the detection element pixels comprise: a common upper electrode (60); a detection layer (50); and lower discrete electrodes (40). Said device includes a metal mesh which: is connected to said upper electrode; comprises contact pads (80) having at least one metal portion, said contact pads being incorporated in said detection layer; positioned such as to connect to said network of control rows and columns. The invention also relates to a method for manufacturing the matrix detection device according to the invention.