Infrared Image Sensor Wavelength Conversion Layer
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Solution Overview
Problem
Conventional infrared image sensors suffer from reduced sensitivity due to the deep penetration of infrared light into semiconductor substrates, leading to light loss and decreased photoelectric conversion efficiency.
Innovation Solution
Incorporating a wavelength conversion layer, such as glass doped with ZnSe nanocrystals, to convert infrared light into visible light, which is then collected by photodiodes, thereby reducing light loss and enhancing sensitivity. Additionally, optical filters and microlenses are used to optimize light transmission and collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If infrared light is directly incident on the photoelectric conversion element, then the structure is simple, but the penetration depth is excessive causing light loss and reduced sensitivity
Solution Approach 1:
A wavelength conversion layer is introduced as an intermediary component between the infrared light source and the photoelectric conversion element. This layer converts infrared light (first wavelength band) into visible light (second wavelength band) through photoluminescence, enabling the photoelectric conversion element to detect infrared radiation indirectly with improved efficiency and reduced light loss.
Solution Approach 2:
The patent changes the wavelength parameter of light by introducing a wavelength conversion layer that transforms infrared wavelengths into visible wavelengths. This parameter transformation allows the photoelectric conversion element to effectively detect infrared radiation by converting it to a wavelength range where the detector has higher quantum efficiency.
2Reliability
If the wavelength conversion layer is added to convert infrared light to visible light, then the photoelectric conversion efficiency is improved, but the device complexity increases
Solution Approach 1:
The wavelength conversion layer serves as a mediator that bridges the mismatch between infrared light emission and the visible-range sensitivity of standard silicon photodiodes. By converting infrared photons to visible photons, it enables efficient detection without requiring complex specialized infrared detector structures.
Solution Approach 2:
The patent employs composite materials in the wavelength conversion layer, such as phosphor materials or quantum dots, combined with a transparent matrix material. This composite structure enables effective infrared-to-visible conversion while maintaining optical transparency and structural integrity, achieving high conversion efficiency with a relatively simple layered architecture.
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 conversion of infrared light to visible light reduces penetration depth, increasing photocharge generation and improving the photoelectric conversion efficiency and sensitivity of the image sensor.
Implementation Method 1
a wavelength conversion layer disposed above the photoelectric conversion element to convert light within a first wavelength band into light within a second wavelength band shorter than the first wavelength band
Implementation Method 2
an image sensor comprises a photoelectric conversion element... to supply the converted light to the photoelectric conversion element
Data Source
AI summary
An image sensor comprises a photoelectric conversion element receiving light to accumulate photocharges, and a wavelength conversion layer formed above the photoelectric conversion element to convert light within a first wavelength band into light within a second wavelength band shorter than the first wavelength band and supply the converted light to the photoelectric conversion element.