Graphene Plasmon Detector All-Electrical Readout
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Solution Overview
Problem
Existing plasmon detectors face challenges such as complex fabrication processes, off-chip detection, and the need for cryogenic temperatures, as well as requiring plasmon energy above the semiconductor band gap or relying on thermal conversion, which limits their efficiency and ease of production.
Innovation Solution
A plasmon detector using a graphene waveguide with ohmic contacts for all-electrical detection, where the charge carrier dynamics are described by hydrodynamic theory, enabling direct and efficient detection of plasmons without frequency limitations, and simplifying the fabrication process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical readout or photodetector conversion is used to detect plasmons, then detection capability is achieved, but device complexity increases and fabrication becomes sophisticated
Solution Approach 1:
The patent replaces optical detection mechanisms (photodetectors, optical readout) with an electrical detection mechanism using a field-effect transistor. The plasmon-induced charge carriers are directly detected as electrical signals through the FET, eliminating the need for complex optical components and simplifying the overall device structure while maintaining detection capability.
2Productivity
If superconducting detectors are used for on-chip plasmon detection, then detection efficiency improves, but the device requires cryogenic temperatures
Solution Approach 1:
The patent changes the operating temperature parameter from cryogenic (required by superconducting detectors) to room temperature by using a conventional field-effect transistor instead of superconducting materials. This parameter change makes the device more practical for general applications while maintaining adequate detection efficiency through the electrical detection mechanism.
3Ease of operation
If semiconductor-based detection is used, then electrical detection is achieved, but plasmon energy must be larger than the semiconductor band gap
Solution Approach 1:
The patent enhances the versatility of the detection system by using a field-effect transistor that can detect a broad range of plasmon frequencies regardless of the semiconductor band gap. The FET's gate structure allows it to respond to various charge carrier types and energies, making the detector universally applicable to different plasmon sources and frequencies without being constrained by material band gap limitations.
4Ease of operation
If nanowire field-effect transistor is positioned near the plasmonic waveguide for detection, then electrical detection is enabled, but near-field coupling causes quenching of the plasmon
Solution Approach 1:
The patent introduces a dielectric layer as an intermediary between the plasmonic waveguide and the field-effect transistor. This intermediate layer provides electrical insulation while allowing the electric field of the plasmon to penetrate through and modulate the FET channel. This mediator enables electrical detection without direct contact, thus avoiding plasmon quenching while maintaining detection functionality.
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 allows for efficient, versatile, and cost-effective all-electrical plasmon detection at room temperature, with a simpler device architecture that does not require plasmon energy above the semiconductor band gap, overcoming the limitations of prior art devices.
Implementation Method 1
a strip-shaped waveguide of material adapted to propagate a plasmon when excited by an incident beam of light
Implementation Method 2
the charge carrier dynamics can be described by hydrodynamic theory. Non-linearities enable the emergence of a rectified (i.e. DC) component of the AC electric field of a propagating plasmon
Implementation Method 3
Non-linearities enable the emergence of a rectified (i.e. DC) component of the AC electric field of a propagating plasmon
Implementation Method 4
a series of probe electrodes are placed along one side edge of the waveguide with each of the probe electrodes arranged in ohmic contact with a minimal area overlap of the waveguide
Data Source
Figure 1~2
Figure 3
AI summary
A plasmon detector comprising a strip-shaped waveguide (10) of material adapted to generate a plasmon when excited by an incident beam of light, the waveguide being adapted to guide the plasmon along its length direction (x). The detector comprises at least one probe electrode (21, 22, 23; 31, 32, 33) arranged in ohmic contact with a minimal area overlap (10a) of the waveguide (10) at one of opposite side edges (11, 12) thereof, and a reference electrode (40) arranged in ohmic contact with one of opposite ends of the waveguide. A DC electric potential difference (δV) is measurable between probe electrode (21, 22, 23; 31, 32, 33) and reference electrode (40), the potential difference being related to an AC electric field of plasmon propagating in the waveguide (10).