Copper Halide Photosensor Vertical Stacking for Quantum Efficiency
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Solution Overview
Problem
Conventional active pixel sensors with multiple wavelength capabilities occupy a large area per pixel and suffer from reduced quantum efficiency due to smaller photodiode sizes relative to light wavelengths, leading to decreased light absorption and carrier generation.
Innovation Solution
A color photosensor structure featuring vertically aligned junctions on a silicon semiconductor substrate, including copper halide regions of specific polarities, which form photodiodes optimized for different light wavelengths, enhancing optical efficiency and reducing sensor size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If sensors are arranged horizontally on a semiconductor substrate, then multiple wavelengths can be detected, but the area occupied per pixel becomes large
Solution Approach 1:
The patent transitions from horizontal arrangement of multiple wavelength sensors to a vertical stacking architecture where silicon-based and copper halide-based photodetectors are stacked in the depth direction. This dimensional change allows multiple wavelength detections to coexist in a compact vertical configuration rather than spreading horizontally, thereby reducing pixel area while maintaining multi-wavelength capability
Solution Approach 2:
The sensor is segmented into multiple functional layers with different materials optimized for different wavelength ranges. The silicon-based photodetector handles certain wavelengths while copper halide-based photodetectors handle others, with each layer independently optimized. This segmentation allows efficient spectral division without requiring large horizontal space
2Area of stationary object
If photodiode size is reduced to decrease sensor size, then pixel area decreases, but quantum efficiency drops rapidly
Solution Approach 1:
The patent employs composite material architecture combining silicon-based and copper halide-based photodetectors in a vertical stack. Each material is selected for its optimal optical absorption characteristics at specific wavelengths. This composite approach maintains high quantum efficiency for each wavelength band even with reduced lateral dimensions, as the vertical stacking provides sufficient light absorption path length without requiring large pixel area
Solution Approach 2:
Different regions of the vertical stack are optimized for different wavelengths with locally appropriate materials. The silicon layer is optimized for its specific wavelength range while copper halide layers are optimized for theirs, with each local region having the optimal material properties for its function. This local optimization maintains high quantum efficiency despite overall sensor miniaturization
3Ease of manufacture
If silicon-based photodetectors are used, then manufacturing is established, but light absorption efficiency decreases
Solution Approach 1:
The patent creates a composite detector system where silicon-based photodetectors are combined with copper halide-based photodetectors in a vertical stack. The silicon layer maintains manufacturing advantages from established CMOS processes, while copper halide layers are integrated using compatible deposition techniques. Each material contributes its optimal light absorption characteristics, achieving superior overall optical efficiency while retaining manufacturing feasibility
Solution Approach 2:
The vertical stacking architecture acts as an intermediary structure that allows both silicon and copper halide materials to function optimally. The layered configuration enables each material to absorb light in its optimal wavelength range without interfering with the other, mediating between the manufacturing advantages of silicon and the optical advantages of copper halide
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 use of copper halide regions improves quantum efficiency and allows for a smaller photosensor size by optimizing light absorption across various wavelengths, surpassing the limitations of conventional silicon-based sensors.
Implementation Method 1
at least one of the junctions is a junction of a copper halide region of a first polarity and a silicon region of a second polarity... a junction between the first copper halide region and the doped region being formed at a depth that is an absorption length of a second light wavelength in silicon or copper halide
Implementation Method 2
as the size of the photosensor becomes smaller, the size of the photodiode becomes smaller than the wavelength of light, and the probability that incident light generates a carrier decreases
Data Source
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AI summary
The present invention relates to a structure of an photosensor structure having improved optical properties by including a copper halide region, and a method of manufacturing the same. The photosensor structure includes a silicon semiconductor substrate and junctions formed in the silicon semiconductor substrate and having regions of at least three opposite polarities. The junctions may be arranged substantially vertically aligned with each other, and at least one of the junctions may be a junction of a copper halide region of a first polarity and a silicon region of a second polarity. Accordingly, the quantum efficiency is improved by the optical characteristics of the copper halide, and the effect of reducing the size of the manufactured photosensor can be obtained.