Organic Pixel With Insulation Layer For Charge Transfer
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Solution Overview
Problem
Current organic photo-diodes in image sensors face challenges in efficiently performing charge accumulation and transfer operations, leading to suboptimal image quality due to limitations in photo-electric conversion efficiency and noise reduction.
Innovation Solution
An organic pixel structure is developed with a semiconductor substrate, an interconnection layer, and an organic photo-diode featuring an insulation layer and a photo-electric conversion region with electron donating and accepting organic materials, along with a row driver to control charge transfer operations, allowing for efficient charge accumulation and transfer through a 4T operation mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional organic photo-diodes are used in image sensors, then the basic photo-electric conversion function is achieved, but the charge accumulation and transfer operations are inefficient leading to suboptimal image quality
Solution Approach 1:
The organic photo-diode is divided into distinct functional regions: a photo-sensitive region for charge generation, a charge accumulation region for storing photocharges, and a charge transfer region for moving charges to the pixel circuit. This segmentation allows each region to be optimized for its specific function, improving overall charge transfer efficiency and image quality
Solution Approach 2:
An intermediate charge accumulation region is introduced between the photo-sensitive region and the pixel circuit. This intermediary region temporarily stores photocharges before transfer, enabling more efficient charge management and reducing noise, thereby improving image quality without sacrificing transfer efficiency
2Ease of manufacture
If the photo-diode structure is simplified for ease of manufacture, then manufacturing complexity is reduced, but photo-electric conversion efficiency and noise reduction performance deteriorate
Solution Approach 1:
The patent employs multiple organic material layers with different energy levels (HOMO and LUMO levels) to create favorable charge transfer pathways. By carefully selecting and stacking materials with appropriate energy level alignments, efficient charge separation and transfer are achieved while maintaining compatibility with standard organic semiconductor manufacturing processes
3Reliability
If thermal noise is reduced to improve signal-to-noise ratio, then sensitivity is improved, but device complexity increases due to additional noise control mechanisms
Solution Approach 1:
The patent converts potential sources of noise into beneficial functions by designing the organic photo-diode structure to naturally suppress thermal noise through proper energy level alignment and charge carrier management. The multi-layer organic structure inherently filters noise while maintaining sensitivity, avoiding the need for additional complex noise control mechanisms
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 enhances image sensor performance by reducing thermal noise, improving fill factor, and increasing sensitivity and signal-to-noise ratio, while also allowing for a more compact image sensor design with reduced noise and improved optical efficiency.
Implementation Method 1
A photo-diode may have a P-N junction structure or a PIN structure and generates free electrons and holes by using a photo-electric effect
Implementation Method 2
The photo-electric conversion region may include an electron donating organic material and an electron accepting organic material
Data Source
AI summary
Provided is an organic pixel, which includes a semiconductor substrate including a pixel circuit, an interconnection layer having a first contact and a first electrode formed on a semiconductor substrate, and an organic photo-diode formed on the interconnection layer. For example, the organic photo-diode includes an insulation layer formed on the first electrode, a second electrode and a photo-electric conversion region formed between the first contact, the insulation layer and the second electrode. The photo-electric conversion region includes an electron donating organic material and an electron accepting organic material. The organic photo-diode may further include a second contact electrically connected to the first contact. The horizontal distance between the second contacts and the insulation layer may be less than or equal to a few micrometers, for example, 10 micrometers.