Infrared Detector with Segmented Absorbers and Reflectors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Infrared detector arrays require cryogenic cooling to reduce noise current, which leads to bulky and unreliable systems, and existing technologies struggle to achieve high quantum efficiency and low front-side reflection across multiple wavelength bands.
Innovation Solution
The use of discrete trapezoidal-shaped absorber regions with a metal reflector and pyramidal anti-reflection structures on both sides of the detector, reducing absorber volume and enhancing light trapping and absorption efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cryogenic cooling is used to reduce noise current, then dark current is reduced, but the system becomes bulky and less reliable
Solution Approach 1:
The patent changes the operating temperature parameter from cryogenic (77K) to higher temperatures (150-200K) by modifying the detector structure to include discrete absorber regions with reduced volume, allowing thermal management without cryogenic cooling while maintaining low dark current
Solution Approach 2:
The light-absorbing layer is segmented into discrete absorber regions (islands) separated by spacer material, reducing the total volume of light-absorbing material and thereby reducing dark current generation, which enables operation at higher temperatures without bulky cooling systems
2Reliability
If discrete absorber regions are used to reduce absorber volume, then dark current is reduced, but manufacturing complexity increases
Solution Approach 1:
The light-absorbing layer is divided into discrete absorber regions (islands) separated by spacer material, creating a segmented structure that reduces absorber volume and dark current while maintaining manufacturability through standard semiconductor fabrication processes
Solution Approach 2:
A spacer material is introduced as an intermediary between discrete absorber regions, providing structural separation and enabling precise control of absorber geometry while simplifying the fabrication process through sequential deposition and etching steps
3Ease of manufacture
If pyramidal structures are added for anti-reflection, then front-side reflection is reduced, but manufacturing steps increase
Solution Approach 1:
Pyramidal structures with curved or sloped surfaces are formed on the front surface of the detector to reduce front-side reflection through geometric phase control and multiple internal reflections, improving light coupling efficiency across broad wavelength ranges
Solution Approach 2:
Pyramidal anti-reflection structures are formed preliminarily during the fabrication process before final detector assembly, integrating optical optimization into the manufacturing sequence without requiring separate post-processing steps
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 configuration allows for operation at higher temperatures (150-200° K) with reduced dark current and high quantum efficiency, achieving low front-side reflection and improved noise performance across a broad wavelength range.
Implementation Method 1
a separate metal reflector and contact layer which contacts or adjoins the tips of the multiple discrete regions of the first optical absorber material
Implementation Method 2
pyramidal anti-reflection structures on both sides of the detector
Implementation Method 3
multiple discrete regions of a first optical absorber material... each discrete region having a geometric shape which it shares in common with the other discrete regions of the first optical absorber material
Data Source
AI summary
An infrared photo-detector with multiple discrete regions of a first absorber material. These regions may have geometric shapes with sloped sidewalls. The detector also may include a second absorber region comprising a second absorber material that absorbs light of a shorter wavelength than the light absorbed by the multiple discrete absorber regions of the first absorber material. The geometric shapes may extend only through the first absorber material. Alternatively, the geometric shapes may extend partially into the second absorber region. The detector has a metal reflector coupled to the multiple discrete absorber regions. The detector also has a substrate containing the discrete absorber regions and the second absorber region. The substrate can further include geometric shaped features etched into the substrate, with those features formed on the side of the substrate opposite the side containing the discrete absorber regions and the second absorber region.