Plasmonic Waveguide Photodetector With Schottky MSM Core
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Solution Overview
Problem
In plasmonic waveguide photodetectors, 50% or more of the light energy is lost due to inefficient photoelectric conversion at the Au-Si interface, and coupling with symmetric Si waveguides results in high coupling loss, reducing conversion efficiency.
Innovation Solution
A plasmonic waveguide with a semiconductor core and metal source electrodes on both sides, along with a drain electrode on the upper surface, forming a lateral metal-semiconductor-metal structure, which improves energy conversion efficiency without altering the symmetry of the propagation mode, and a mode converter with a tapered structure for efficient light coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a plasmonic waveguide with metal electrodes is used to confine light in subwavelength area, then light confinement capability is improved, but photoelectric conversion efficiency deteriorates because 50% or more of light energy is lost at the Au-Si interface
Solution Approach 1:
The patent applies local quality by creating asymmetric metal electrode configurations where different metal materials are used at different locations along the waveguide. Specifically, the first metal material is used at a first location and a second metal material is used at a second location, allowing each region to be optimized for its specific function - one region for effective light confinement and another for efficient photoelectric conversion, thereby resolving the contradiction between subwavelength confinement and conversion efficiency
Solution Approach 2:
The patent employs asymmetry by deliberately designing the plasmonic waveguide with non-uniform metal electrode distribution. The asymmetric arrangement of different metal materials breaks the symmetry that causes uniform but inefficient photoelectric conversion, enabling differentiated functional zones that simultaneously achieve subwavelength light confinement and enhanced energy conversion efficiency
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
Enhances energy conversion of incident light into electrons with improved sensitivity and conversion efficiency, maintaining the symmetry of the propagation mode and reducing coupling losses.
Implementation Method 1
due to the excitation of metal surface plasmon polaritons (SPPs), the light distributes with a relatively high intensity at the interface between the core 302 (Si) and the first metal electrode 303 (Au) and the interface between the core 302 (Si) and the second metal electrode 304 (Ti)
Implementation Method 2
When the energy of the excited wavelength (1.5 μm) travels over the interface between the core 302 and the first metal electrode 303 and the height of the Schottky barrier between the core 302 and the second metal electrode 304, the charge carriers excited in the first metal electrode 303 and the second metal electrode 304 can enter the core 302. The principal of such light detection is referred to as internal photoemission (IPE).
Data Source
AI summary
An optical device includes a core formed on a substrate, a first source electrode and a second source electrode formed in contact with both side surfaces of the core interposed between the first source electrode and the second source electrode, and a drain electrode formed in contact with an upper surface of the core. The core, the first source electrode, and the second source electrode together form a plasmonic waveguide. The first source electrode and the second source electrode are Schottky coupled to the core.