InGaAsP Night Vision Sensor Wavelength Cutoff Optimization
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Solution Overview
Problem
Night vision image sensors face challenges in detecting light at wavelengths above 1.4 µm on moonless nights, leading to limited performance due to high dark current and power consumption requirements, especially in portable applications.
Innovation Solution
A semiconductor absorption layer with a long wavelength response cutoff between 1.25 to 1.4 µm is used in night vision cameras, optimizing the In1-xGa x As y P 1-y composition to match the InP lattice, which reduces dark current and power consumption while maintaining sensitivity in the SWIR band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the long wavelength response cutoff is extended beyond 1.4 µm to detect more light on moonless nights, then the light detection capability is improved, but the dark current increases significantly
Solution Approach 1:
The patent optimizes the semiconductor composition parameters (x and y in In1-xGaxAsyP1-y) to precisely control the long wavelength response cutoff to fall within 1.25 to 1.4 µm. This parameter optimization allows the sensor to detect light in the 950-1400 nm band while excluding wavelengths that generate excessive dark current, thereby resolving the contradiction between light detection capability and dark current generation.
2Use of energy by moving object
If the semiconductor composition is optimized to reduce dark current, then the power consumption is reduced, but the sensitivity in SWIR band may be compromised
Solution Approach 1:
The patent simultaneously optimizes multiple composition parameters (x and y values) to achieve a precise balance: the In1-xGaxAsyP1-y composition is tuned so that the long wavelength cutoff falls within 1.25 to 1.4 µm, which reduces dark current and power consumption while maintaining quantum efficiency in the 950-1400 nm SWIR band. This multi-parameter optimization resolves the contradiction between power consumption and sensitivity.
Solution Approach 2:
The patent uses a composite semiconductor material In1-xGaxAsyP1-y that combines properties of different semiconductor compounds. By adjusting the composition ratios (x and y), the material achieves both low dark current characteristics and high sensitivity in the SWIR band, resolving the contradiction between power consumption and sensitivity through material composition engineering.
3Manufacturing precision
If the InGaAsP composition is optimized for lattice matching to InP, then the manufacturing precision is improved, but the wavelength response range is limited
Solution Approach 1:
The patent optimizes the composition parameters (x and y) of In1-xGaxAsyP1-y to achieve lattice matching to InP substrate while simultaneously positioning the long wavelength response cutoff within 1.25 to 1.4 µm. This precise parameter control allows the material to maintain high manufacturing quality through lattice matching while achieving the desired wavelength response characteristics for SWIR imaging.
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 significantly reduces dark current and energy consumption, enabling low-light sensitivity and extended battery life in portable night vision systems with improved resolution and reduced cooling requirements, even at elevated temperatures.
Implementation Method 1
A night vision sensor comprising: an active pixel array sensor chip mounted in a header assembly with its backside facing a transparent faceplate; an InP/InGaAsP transferred electron photocathode mounted on the faceplate
Implementation Method 2
an InP/InGaAsP transferred electron photocathode mounted on the faceplate
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The invention relates to a sensor for night vision applications, comprising an InP substrate (500); an InP buffer layer (510) fabricated on one surface of the InP substrate; an InGaAsP absorption layer (515) fabricated on the InP buffer layer; an InP cap layer (525) formed over the absorption layer; wherein the InGaAsP absorption layer limits long wavelength response cutoff to between 1.25 to 1.4µm wavelength. The invention further relates to a night vision apparatus, comprising a sensor that limits long wavelength response cutoff to between 1.25 to 1.4µm wavelength and an imaging chip positioned behind and connected to the sensor and comprising an array having 1600 x 1200 pixels at a 10.8 micron pixel pitch and operating at 60Hz.