Amorphous Silicon Light Sensor Circuit for Higher Biometric Response
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Solution Overview
Problem
Current fingerprint recognition light sensors face issues such as high cost, large volume, image distortion, electrostatic breakdown, environmental sensitivity, and low response rates due to the Poole-Frenkel effect, leading to poor recognition success rates.
Innovation Solution
A light sensor design featuring a substrate with a gate layer, gate insulating layer, active layer patterned to form specific active patterns, source/drain layers, and a protective layer with through holes, incorporating a light sensor circuit with a light sensing transistor using amorphous silicon with a channel region thickness of at least 5000 angstroms, enhancing photo-generated carriers and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the light sensor uses conventional silicon chip-based design, then the sensor structure is compact, but the sensor is prone to electrostatic breakdown and environmental sensitivity resulting in poor performance
Solution Approach 1:
The patent changes the material parameter from conventional silicon chip to amorphous silicon, and adjusts the channel thickness parameter to 5000-20000 angstroms, transforming the sensor's electrical and optical properties to achieve higher reliability and reduced environmental sensitivity
Solution Approach 2:
The patent employs a composite structure combining amorphous silicon active layer with specific gate insulating materials and protective layers, creating a multi-material system that enhances overall sensor reliability while protecting against electrostatic damage and environmental factors
2Reliability
If the light sensor increases the unit area to improve light response, then the light response increases, but the sensor volume increases
Solution Approach 1:
The patent changes the channel thickness parameter to an optimized range of 5000-20000 angstroms, which increases light absorption efficiency per unit area, allowing high light response to be achieved without increasing sensor volume
Solution Approach 2:
Instead of increasing the planar area of the sensor, the patent exploits the thickness dimension by creating a vertically structured active layer with optimized thickness, achieving enhanced light response through the z-dimension while maintaining a compact footprint
3Measurement precision
If the light sensor operates under high load voltage to improve detection capability, then the detection capability improves, but the Poole-Frenkel effect increases decreasing light-dark current ratio and reliability
Solution Approach 1:
The patent changes the material composition to amorphous silicon with specific thickness parameters, which modifies the electrical characteristics to reduce Poole-Frenkel effect, allowing high detection capability to be achieved while maintaining a favorable light-dark current ratio and reliability
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 increases the number of photo-generated carriers and sensitivity, improving fingerprint or palmprint recognition success rates and reducing costs while minimizing sensor volume, thus addressing the limitations of existing sensors.
Implementation Method 1
Material of the first active pattern includes amorphous silicon. A thickness of a channel region of the first active pattern is greater than or equal to 5000 angstroms
Data Source
AI summary
The present application provides a light sensor and a display device. A light sensing transistor and a switching transistor in the light sensor are configured to form a light sensor circuit. In a structural design, amorphous silicon is configured as a first active pattern of the light sensing transistor, so that a thickness of a channel region of the first active pattern is greater than or equal to 5000 angstroms. Therefore, a number of photo-generated carriers of the light sensing transistor is increased, which makes the light sensor have higher responses and increases fingerprint or palmprint recognition success rates.