Plasmonic Single-Photon Detector for Sub-Bandgap IR Sensing
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Solution Overview
Problem
Current single-photon detection elements, such as avalanche photodiodes, face limitations in detecting photons with energy lower than the bandgap of the semiconductor substrate and achieving efficient detection of short-wavelength infrared rays due to insufficient light absorption and noise issues.
Innovation Solution
A single-photon detection element is designed with a substrate having plasmonic nanopatterns on its surface, a high-concentration doping region, and a well structure, which enhances light absorption and reduces noise by forming a Schottky junction and adjusting charge injection characteristics, allowing for detection of photons with energy less than the bandgap and improving near-infrared efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional semiconductor substrate is used for photon detection, then the device structure is simple and manufacturing is easy, but photons with energy lower than the bandgap cannot be detected
Solution Approach 1:
The patent employs a composite structure combining a semiconductor substrate with metal nanopatterns exhibiting plasmonic properties. This composite configuration enables the detection of photons with energies below the semiconductor bandgap by utilizing plasmon resonance in the metal nanoparticles, which can be tuned to specific wavelengths including the infrared range, thereby extending detection capability beyond the limitations of the semiconductor material alone.
Solution Approach 2:
The patent modifies the optical response parameters of the detection system by introducing metal nanopatterns with specific geometries, sizes, and arrangements. These parameter changes enable plasmon resonance at desired wavelengths, allowing the device to detect photons with energies lower than the semiconductor bandgap while maintaining the original semiconductor substrate for structural simplicity and manufacturability.
2Adaptability or versatility
If the semiconductor substrate material is changed to extend detection to lower energy photons, then the detection capability improves, but manufacturing complexity and cost increase
Solution Approach 1:
The patent divides the detection function into two distinct components: the semiconductor substrate provides the basic photodetection capability and structural support, while the added metal nanopatterns specifically handle the extension to lower energy photon detection. This segmentation allows each component to be optimized independently and integrated using existing manufacturing processes, avoiding the need to change the entire substrate material.
Solution Approach 2:
The metal nanopatterns act as an intermediary layer between the incident photons and the semiconductor substrate. These nanopatterns absorb and concentrate electromagnetic energy at specific wavelengths through plasmon resonance, then transfer this energy to the semiconductor substrate, enabling indirect detection of photons that would otherwise be below the detection threshold of the semiconductor material.
3Device complexity
If standard photodetection methods are used, then the device structure is simple, but detection efficiency for near-infrared and longer wavelengths is poor
Solution Approach 1:
The patent utilizes metal nanopatterns with curved or spherical geometries that support localized surface plasmon resonance. These curved structures concentrate electromagnetic fields at their surfaces and tips, creating enhanced local fields that improve the absorption of near-infrared and longer wavelength photons, thereby significantly boosting detection efficiency without requiring complex multi-layer device structures.
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 solution enables effective detection of photons with energy lower than the bandgap and enhances near-infrared efficiency, improving the detection of short-wavelength infrared rays while reducing noise and premature breakdown, thereby enhancing the performance of single-photon detection elements.
Implementation Method 1
a plurality of plasmonic nanopatterns provided on the second surface... enhance light absorption by generating plasmons and hot carriers
Implementation Method 2
generate plasmons and hot carriers to overcome the bandgap limitation
Implementation Method 3
a first well provided between the substrate region and the high-concentration doping region... reduce noise signals
Data Source
AI summary
A single-photon detection element includes a substrate including a first surface and a second surface located opposite to each other, and a plurality of plasmonic nanopatterns provided on the second surface, wherein the substrate includes a high-concentration doping region provided adjacent to the first surface, a substrate region provided between the high-concentration doping region and the plurality of plasmonic nanopatterns, and a first well provided between the substrate region and the high-concentration doping region.