Image Sensor Pixel Unit Using Quantum Film and Oxide Semiconductor Transistor
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Solution Overview
Problem
CMOS image sensors face challenges in achieving higher sensitivity and resolution due to smaller pixel sizes, leading to reduced sensitivity, as well as demands for low power consumption and noise reduction, particularly in applications like motion detection.
Innovation Solution
The operating method incorporates a quantum film photoelectric conversion unit and an oxide semiconductor transistor, with a capacitor unit charged by electrons from the photoelectric conversion unit, allowing for longer data retention and simplified readout processes, enabling enhanced sensitivity and resolution while supporting motion detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixel size is reduced to achieve higher resolution, then resolution is improved, but sensitivity deteriorates
Solution Approach 1:
The patent changes the material parameter of the photoelectric conversion layer by using quantum films with specific quantum confinement effects, allowing smaller pixels to maintain high sensitivity through quantum size effects rather than relying solely on pixel area
Solution Approach 2:
The patent employs composite material structures combining quantum films with specific semiconductor materials to create photoelectric conversion units that achieve both small size and high sensitivity through material composition optimization
2Device complexity
If conventional transistors are used in pixel units, then device complexity is reduced, but data retention time deteriorates due to leakage current
Solution Approach 1:
The patent changes the material parameter of the transistor by using oxide semiconductor materials with wide bandgap characteristics, which inherently provide extremely low leakage current and enable long data retention without requiring additional retention circuitry
Solution Approach 2:
The patent replaces conventional short-retention transistors with oxide semiconductor transistors that provide inherently long retention characteristics, eliminating the need for complex retention circuits while simplifying the overall pixel unit design
3Reliability
If higher sensitivity is pursued through larger pixels, then sensitivity is improved, but device area increases
Solution Approach 1:
The patent changes the photoelectric conversion mechanism by utilizing quantum films with enhanced quantum efficiency, allowing small pixels to achieve high sensitivity through improved photon-to-electron conversion rather than increasing pixel area
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 improves the sensitivity and resolution of image sensors, achieves longer data retention, simplifies readout and signal processing, and supports high-resolution and low-power consumption requirements, including motion detection capabilities.
Implementation Method 1
a quantum film photoelectric conversion unit, and the first control unit includes an oxide semiconductor transistor... The capacitor unit is charged by electrons emitted from the photoelectric conversion unit when the photoelectric conversion unit is excited by light
Data Source
AI summary
An operating method of an image sensor includes the following steps. The image sensor includes at least one pixel unit. The pixel unit includes a photoelectric conversion unit, a first control unit, a capacitor unit, and a sensing unit. The photoelectric conversion unit includes a quantum film photoelectric conversion unit, and the first control unit includes an oxide semiconductor transistor. The capacitor unit is coupled to the first control unit, and the sensing unit is configured to sense signals at a sense point coupled between the first control unit and the sensing unit. The pixel unit is discharged before a readout operation. The capacitor unit is charged by electrons emitted from the photoelectric conversion unit when the photoelectric conversion unit is excited by light. Signals at the sense point are then sensed by the sensing unit.