Vertical Transistor X-Ray Detector Layout for Higher Photo Current
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Solution Overview
Problem
Existing digital X-ray detectors face challenges in improving photo current, photoconductive layer area, and protection of transistors from external light, leading to suboptimal performance and efficiency.
Innovation Solution
A digital X-ray detector design featuring a pin diode with a photoconductive layer and a vertical transistor disposed on the side surface of the photoconductive layer, overlapping with the first electrode, which enhances the photoconductive layer area and protects the transistor from external light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the area of the photoconductive layer is increased to improve photo current, then the photo current is improved, but the transistor is exposed to external light causing performance degradation
Solution Approach 1:
The transistor is repositioned from a planar configuration to a vertical configuration, moving it to a different spatial dimension (above the photoconductive layer). This dimensional change allows the transistor to be positioned where it does not receive harmful external light while still maintaining electrical connection to the photoconductive layer through the first electrode.
Solution Approach 2:
The first electrode serves as an intermediary element that performs dual functions: it collects electrical signals from the photoconductive layer and provides a light-blocking barrier between the photoconductive layer and the transistor. This intermediary structure enables the transistor to be positioned above the photoconductive layer without direct light exposure while maintaining electrical connectivity.
2Device complexity
If a horizontal transistor layout is used, then the device structure is simple, but the photoconductive layer area is reduced and photo current is insufficient
Solution Approach 1:
The transistor is oriented vertically rather than horizontally, changing its spatial arrangement from a planar layout to a three-dimensional configuration. This vertical orientation allows the transistor to be positioned above the photoconductive layer, maximizing the photoconductive layer area without increasing overall device complexity, as the vertical transistor can share the same footprint area.
3Measurement precision
If the photoconductive layer area is increased to improve detection sensitivity, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The transistor is extracted from the planar layout and positioned vertically above the photoconductive layer. This separation allows the photoconductive layer to be maximized in area for improved detection sensitivity while the vertically positioned transistor occupies minimal additional space and can be designed for low power consumption independent of the photoconductive layer size.
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 design improves photo current, increases the area of the photoconductive layer, and reduces power consumption while safeguarding the transistor from external light, resulting in enhanced performance and efficiency.
Implementation Method 1
The X-ray detection device can generate an X-ray image by sensing X-ray light that has passed through the scintillator
Data Source
AI summary
A digital X-ray detector includes a pin diode having a first electrode, a second electrode disposed on the first electrode, and a photoconductive layer disposed between the first electrode and the second electrode. The digital X-ray detector further includes a vertical transistor disposed on a side surface of the photoconductive layer to overlap with the first electrode. Accordingly, it is possible to improve the photo current of the digital X-ray detector.