Infrared Sensor Microcavity Structure for EQE Beyond 1000 Nm
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Solution Overview
Problem
Conventional infrared sensors, particularly those using silicon photodiodes, are limited in their ability to absorb light in the near-infrared wavelength spectrum beyond 1000 nm, restricting their sensitivity and effectiveness in low-illumination environments or biometric applications.
Innovation Solution
The development of a sensor design featuring a light absorbing layer with distinct absorption peaks in different infrared wavelength regions, where the second absorption peak is in a longer wavelength region with lower absorption intensity, and an external quantum efficiency (EQE) spectrum is amplified, allowing effective sensing of light beyond 1000 nm. This design includes a reflective layer, a semi-transmissive layer, and buffer layers to create a microcavity structure that enhances photoelectric conversion in the longer wavelength region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silicon photodiodes are used for infrared sensing, then sensitivity in low-illumination environments is improved, but the ability to absorb light in the near-infrared wavelength spectrum greater than or equal to 1000 nm deteriorates
Solution Approach 1:
The patent uses a composite light absorbing layer comprising a first light absorbing material and a second light absorbing material with different absorption characteristics. The first material absorbs light in a first wavelength range while the second material absorbs light in a second wavelength range, creating a composite structure that extends the overall absorption range to cover both ranges, thereby resolving the contradiction between sensitivity and absorption range.
Solution Approach 2:
The light absorbing layer is segmented into multiple materials with distinct absorption properties. By dividing the absorption function across different materials, each optimized for specific wavelength ranges, the system achieves both high sensitivity in their respective ranges and extended overall coverage beyond what a single silicon photodiode could provide.
2Adaptability or versatility
If a light absorbing layer with dual absorption peaks is designed, then the sensing range in infrared wavelength spectrum is broadened, but the absorption intensity at the second peak deteriorates
Solution Approach 1:
The patent adjusts the thickness of the light absorbing layer and the proportions of different light absorbing materials to optimize the absorption characteristics. By changing these parameters, the system achieves enhanced external quantum efficiency in the second wavelength range while maintaining acceptable absorption intensity, resolving the contradiction between sensing range and absorption intensity.
Solution Approach 2:
The patent introduces a microcavity structure consisting of a reflective layer and a semi-transmissive layer that creates optical resonance effects. This adds a dimensional aspect to light-matter interaction, where the microcavity enhances the external quantum efficiency at specific wavelengths through constructive interference, thereby compensating for lower intrinsic absorption intensity at the second peak.
3Reliability
If buffer layers and reflective layers are added to create a microcavity structure, then photoelectric conversion in the longer wavelength region is enhanced, but the device complexity increases
Solution Approach 1:
The buffer layers and reflective layers serve multiple functions: they act as optical mirrors to create the microcavity resonance effect, provide electrical contact, and contribute to the overall device architecture. By making these components multi-functional, the patent enhances photoelectric conversion efficiency without proportionally increasing complexity, as the same structural elements fulfill multiple roles.
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 sensor achieves improved light sensing performance by amplifying EQE in the longer wavelength region, increasing detection selectivity and broadening the usable range for infrared light sensing, overcoming the absorption limitations of traditional sensors.
Implementation Method 1
The light absorbing layer may have a first absorption spectrum having a first absorption peak in a first infrared wavelength region and a second absorption spectrum having a second absorption peak in a second infrared wavelength region
Implementation Method 2
a first electrode including a reflective layer
Implementation Method 3
configured to generate an electrical current based on photoelectrically converting incident light
Data Source
AI summary
A sensor includes a first electrode, a second electrode facing the first electrode, and a light absorbing layer between the first electrode and the second electrode. The light absorbing layer may have a first absorption spectrum having a first absorption peak in a first infrared wavelength region and a second absorption peak in a second infrared wavelength region, the second infrared wavelength region being a longer wavelength region than the first infrared wavelength region. The second absorption spectrum does not at least partially overlap with the first absorption spectrum. The second absorption spectrum may have a lower absorption intensity than the first absorption spectrum. An external quantum efficiency (EQE) spectrum that is amplified in the second infrared wavelength region is exhibited in the sensor.