Dual Active Layer TFT for Flexible Imaging
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Solution Overview
Problem
Existing thin film transistors using amorphous silicon have limitations due to low mobility and on/off ratio, and high temperature processing, which is disadvantageous for flexible substrates in electronic devices.
Innovation Solution
A semiconductor device with a dual active layer structure comprising a first active layer and a second active layer over a gate metal layer, along with a photodiode structure including N-type, I, and P-type layers, fabricated using a method that involves a flexible substrate assembly process with reduced temperature processing to improve mobility and on/off ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If amorphous silicon is used as the active layer in thin film transistors, then the device can be manufactured with simpler processes, but the mobility and on/off ratio are limited and high temperature processing is required
Solution Approach 1:
The patent employs a composite active layer structure consisting of multiple semiconductor layers with different properties. The first active layer provides good manufacturability while the second active layer enhances mobility and on/off ratio, resolving the contradiction between ease of manufacture and device performance through material composition optimization
Solution Approach 2:
The active layer is divided into multiple segments (first and second active layers) with distinct functions. The first layer handles manufacturing compatibility while the second layer optimizes electrical performance, allowing each segment to address specific requirements without compromising the other
2Ease of manufacture
If amorphous silicon is used as the active layer, then the manufacturing process is simpler, but high temperature processing is required which is disadvantageous for flexible substrates
Solution Approach 1:
The patent changes the material parameters of the active layer by introducing a second semiconductor layer with different thermal characteristics. This composite structure enables low-temperature processing while maintaining manufacturing simplicity, as the second layer can be deposited at lower temperatures than traditional amorphous silicon processes
3Reliability
If a dual active layer structure is implemented, then mobility and on/off ratios are enhanced, but the device complexity increases
Solution Approach 1:
The dual active layer structure segments the functional requirements into two distinct layers: the first layer ensures manufacturability and the second layer optimizes electrical performance. This segmentation allows complex performance requirements to be met while maintaining a relatively simple overall device architecture that can be integrated into existing manufacturing processes
Data Source
AI summary
Some embodiments include an imaging system. The imaging system includes an active matrix pixel array having a flexible substrate and a pixel. The pixel includes a transistor over the flexible substrate, and the transistor includes multiple active layers having a first active layer and a second active layer over the first active layer. Further, the active matrix pixel array also includes a photodiode over the transistor, and the photodiode includes an N-type layer over the transistor, an I layer over the N-type layer, and a P-type layer over the I layer. Meanwhile, the imaging system also includes a flexible scintillator layer over the active matrix pixel array. Other embodiments of related systems and methods are also disclosed.