MISIM Detector Shielding Layer for X-ray Imaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current digital X-ray imaging technologies face challenges in fabricating vertical photodiodes due to complex TFT fabrication processes and high dark currents in lateral MSM photoconductors, leading to reduced fabrication yield and performance issues.
Innovation Solution
A Metal-Insulator-Semiconductor-Insulator-Metal (MISIM) detector element with a conductive shielding electrode layer and carefully selected blocking layers to reduce dark currents and enhance photocurrent, integrated with a readout circuit for improved radiation detection in digital imaging systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a vertical photodiode is fabricated using traditional TFT processes, then radiation detection capability is improved, but fabrication complexity increases and manufacturing yield decreases
Solution Approach 1:
The device is segmented into distinct functional layers: a first electrode, a semiconducting layer, a second electrode, and a conductive shielding electrode layer. This segmentation allows each layer to be optimized independently for its specific function while simplifying the overall fabrication process compared to traditional vertical photodiode structures.
Solution Approach 2:
A conductive shielding electrode layer is introduced as an intermediary element between the electrodes and the semiconducting layer. This shielding layer mediates the electric field distribution and reduces optical crosstalk without requiring complex TFT fabrication modifications, thereby maintaining detection capability while reducing fabrication complexity.
2Ease of manufacture
If lateral MSM photoconductor is used, then fabrication process is simplified, but dark current increases and photoresponse uniformity deteriorates
Solution Approach 1:
The invention transitions from a lateral MSM photoconductor configuration to a vertical stack configuration with the conductive shielding electrode layer positioned between the electrodes and the semiconducting layer. This dimensional change allows for better electric field control and reduced dark current while maintaining fabrication simplicity through sequential layer deposition.
Solution Approach 2:
The conductive shielding electrode layer modifies the electric field parameters within the device, creating a more uniform field distribution across the semiconducting layer. This parameter change reduces dark current generation and improves photoresponse uniformity without complicating the fabrication process.
3Ease of manufacture
If lateral MSM photoconductor is used, then fabrication is easier, but effective quantum efficiency decreases due to space inefficiency
Solution Approach 1:
By stacking the conductive shielding electrode layer vertically between the electrodes and semiconducting layer, the design achieves better space utilization. This vertical arrangement allows for more efficient use of the active area, improving effective quantum efficiency while maintaining lateral fabrication simplicity.
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 MISIM detector element achieves high external quantum efficiency and reduced dark current, resulting in improved image quality and cost-effective digital X-ray imaging by stabilizing pixel capacitance and modifying the electric field for enhanced performance.
Implementation Method 1
electrical charges, generated either electrically or optically by the X-ray radiation within a pixel area
Implementation Method 2
a conductive shielding electrode layer adjacent to one of the first or second electrode
Implementation Method 3
the shielding electrode layer is shaped to shield at least one of the first or second electrode from X-ray radiation
Data Source
AI summary
The disclosure is directed at a detector element that includes a conductive shield electrode, or shield electrode layer that can assist in reducing breakdown and also improve the reliability of the detector element. The detector element includes a substrate layer that supports at least two electrodes and a semiconducting layer. A shield electrode layer is deposited or patterned adjacent at least one of the two electrodes.