Oxide TFT Analog Circuit for High-Sensitivity Signal Detection
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Solution Overview
Problem
Thin film transistors using oxide semiconductors exhibit low on/off ratios and high off-state currents, leading to unstable circuit operation, limited dynamic range, and increased power consumption, which affects signal detection sensitivity and efficiency.
Innovation Solution
The use of a purified oxide semiconductor with reduced hydrogen concentration, forming a channel region with an energy gap of 2 eV or larger, to create a thin film transistor with a carrier concentration of 1×10^14/cm^3 or lower, enhancing the semiconductor's properties for improved circuit performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If oxide semiconductor is used as channel region material, then the transistor can be formed with standard fabrication processes, but the on/off ratio is low and off-state current is high
Solution Approach 1:
The patent changes the physical and chemical parameters of the oxide semiconductor by controlling the carrier concentration to be 1×10^14/cm³ or lower through purification processes. This parameter change transforms the oxide semiconductor from a high-carrier state (typical amorphous oxide) to a low-carrier state, achieving high on/off ratios while maintaining fabrication compatibility
Solution Approach 2:
The patent applies different quality requirements to different regions: the channel region uses highly purified oxide semiconductor with extremely low carrier concentration (1×10^14/cm³ or lower), while other regions can use conventional materials. This local quality differentiation achieves high performance where needed without compromising overall manufacturability
2Productivity
If oxide semiconductor with electron carrier concentration less than 10^18/cm³ is used, then the transistor can be formed, but the on/off ratio is only 10³ due to high off-state current
Solution Approach 1:
The patent pushes the carrier concentration parameter to an extreme low value (1×10^14/cm³ or lower), which is four orders of magnitude lower than conventional oxide semiconductors. This extreme parameter change enables the on/off ratio to reach 10⁸ or higher, solving the fundamental limitation of oxide semiconductor-based transistors
3Adaptability or versatility
If conventional oxide semiconductor is used in analog circuit, then the circuit can be implemented, but the dynamic range is limited and signal detection sensitivity is insufficient
Solution Approach 1:
By changing the carrier concentration parameter to 1×10^14/cm³ or lower, the patent enables analog circuits to achieve sufficient signal detection sensitivity and wide dynamic range, making oxide semiconductor transistors suitable for precision analog applications
4Ease of operation
If oxide semiconductor with high off-state current is used, then the transistor can operate, but power consumption increases due to unnecessary current flow
Solution Approach 1:
By changing the carrier concentration parameter to extremely low values (1×10^14/cm³ or lower), the patent reduces off-state current to negligible levels, thereby minimizing power consumption while maintaining full transistor operation capability
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 approach results in a semiconductor device with increased signal detection sensitivity, wider dynamic range, and reduced power consumption, enabling stable and efficient operation of analog circuits.
Implementation Method 1
forming a channel region with an energy gap of 2 eV or larger
Implementation Method 2
create a thin film transistor with a carrier concentration of 1×10^14/cm^3 or lower
Data Source
AI summary
An object is to obtain a semiconductor device having a high sensitivity in detecting signals and a wide dynamic range, using a thin film transistor in which an oxide semiconductor layer is used. An analog circuit is formed with the use of a thin film transistor including an oxide semiconductor which has a function as a channel formation layer, has a hydrogen concentration of 5×1019 atoms/cm3 or lower, and substantially functions as an insulator in the state where no electric field is generated. Thus, a semiconductor device having a high sensitivity in detecting signals and a wide dynamic range can be obtained.