Oxide Semiconductor Amplifying Transistor for High-Sensitivity Radiation Detection
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Solution Overview
Problem
Radiation detectors employing the APS method face challenges in achieving high sensitivity due to insufficient examination of current characteristics of the TFT, leading to difficulties in detecting smaller charges compared to PPS methods.
Innovation Solution
A radiation detector configuration that includes a light receiving device, such as a photodiode, and an amplifying transistor with a channel layer containing oxide semiconductors with a non-amorphous crystal structure, including indium and zinc, where the light receiving device is positioned above the amplifying transistor, allowing for enhanced signal amplification and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a radiation detector based on PPS method is used, then the device structure is simpler, but the detection sensitivity is lower and smaller charges cannot be detected
Solution Approach 1:
The patent combines the light receiving device and the amplifying transistor into a single integrated pixel structure. The amplifying transistor is formed in the same semiconductor substrate as the light receiving device, merging the signal generation and amplification functions into one compact unit, thereby achieving high sensitivity without significantly increasing device complexity
Solution Approach 2:
The amplifying transistor is configured to be conductive during the light receiving period, performing signal amplification in advance before readout. This preliminary amplification action ensures that even small charges generated by the light receiving device are sufficiently amplified before being read out, thereby improving detection sensitivity
2Measurement precision
If the amplifying transistor uses conventional semiconductor material, then the manufacturing process is mature, but the amplification performance is insufficient for detecting small charges
Solution Approach 1:
The patent changes the material parameter of the amplifying transistor from conventional semiconductor to oxide semiconductor. This material parameter change provides superior electrical characteristics with lower off-state current and higher mobility, enabling effective amplification of small charges while maintaining manufacturing feasibility through established oxide semiconductor processing techniques
3Measurement precision
If the light receiving device receives light without the amplifying transistor conductive, then the circuit operation is simpler, but the signal amplification is insufficient
Solution Approach 1:
The amplifying transistor maintains a conductive state during the light receiving period, ensuring continuous signal amplification throughout the entire charge accumulation phase. This continuous amplification action ensures that even small charges are sufficiently amplified before readout, improving signal detection capability while the conduction control is achieved through simple gate voltage management
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 enables a high-sensitivity radiation detector by amplifying electrical signals effectively, even with small changes in gate voltage, thereby improving detection capabilities.
Implementation Method 1
a light receiving device that receives light obtained from radiation and that converts the light into an electrical signal
Data Source
AI summary
[Object] To achieve a high-sensitivity radiation detector.[Solution] An amplifying transistor (3) is configured such that a photodiode (1) receives light with the amplifying transistor (3) conductive.