Optical Sensor Barrier Layer for Low-Leakage Fingerprint Sensing
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Solution Overview
Problem
Fingerprint sensors integrated with display devices face challenges in minimizing leakage current, which affects the accuracy of fingerprint sensing due to noise in the sensing current.
Innovation Solution
The implementation of a barrier layer on the photoelectric element, specifically formed of an inorganic film, spaced apart from the first electrode and in contact with the second electrode, helps minimize leakage current by preventing side surface damage and reducing noise in the sensing current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional photoelectric element structure is used without additional protective layers, then the device complexity is low, but leakage current occurs due to side surface damage affecting sensing accuracy
Solution Approach 1:
The barrier layer is formed on the side surface of the photoelectric element before final assembly and testing, preventing side surface damage and leakage current from occurring in the first place. This preliminary protective measure eliminates the need for complex post-processing or repair mechanisms.
Solution Approach 2:
The barrier layer acts as an intermediary protective structure between the photoelectric element's sensitive semiconductor material and the external environment. This intermediate layer blocks harmful factors causing leakage current while maintaining the element's functional integrity.
2Reliability
If the barrier layer is positioned close to the first electrode, then the structural complexity is minimized, but leakage current increases due to insufficient protection of the photoelectric element
Solution Approach 1:
The barrier layer is extended into the vertical dimension, covering the side surface of the photoelectric element rather than only the top surface. This three-dimensional protective configuration effectively blocks leakage current paths while maintaining a relatively simple overall structure.
3Measurement precision
If the insulating layer is made thinner to reduce device thickness, then the overall device size is reduced, but noise in the sensing current increases affecting measurement precision
Solution Approach 1:
The insulating layer is strategically positioned and dimensioned to provide adequate noise shielding only where required for signal quality, rather than uniformly throughout the entire device. This localized approach maintains signal quality while minimizing unnecessary thickness.
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 solution effectively reduces leakage current, enhancing the accuracy of fingerprint sensing by minimizing noise in the sensing current, thereby improving the overall performance of fingerprint recognition systems.
Implementation Method 1
A fingerprint sensor integrated display device uses a sensor that can sense light. A fingerprint sensor integrated display device that uses a light sensing method uses a light emitting element provided in a pixel as a light source, and includes an optical sensor array.
Data Source
AI summary
An optical sensor includes a substrate, a photoelectric element disposed on the substrate and that includes a first electrode, an intermediate layer disposed on the first electrode, and a second electrode disposed on the intermediate layer, a barrier layer disposed on the second electrode, an insulating layer that covers the photoelectric element and the barrier layer, and a bias electrode disposed on the insulating layer and electrically connected to the second electrode. The barrier layer is spaced apart from the first electrode.