Avalanche Photodiode Plasmonic Structure for Higher Quantum Efficiency
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Solution Overview
Problem
Existing photodetectors face challenges in increasing quantum efficiency, particularly in structures utilizing avalanche multiplication and surface plasmon resonance.
Innovation Solution
A photodetector design incorporating an avalanche photodiode with a plasmonic structure portion on the light incidence surface, featuring unit structures with specific height and surface orientations to enhance light diffraction through localized surface plasmon resonance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a PonN-type structure is used with a p-type first semiconductor region and n-type second semiconductor region, then the device structure is simplified and manufacturing is easier, but the amount of light absorption in the p-type semiconductor region becomes small
Solution Approach 1:
The patent introduces a plasmonic structure portion with three-dimensional unit structures (having height, width, and depth) on the light incidence surface. This adds a vertical dimension (height of 100-250 nm) to the otherwise planar semiconductor layers, creating localized surface plasmon resonance that diffracts light into the p-type region and increases the effective optical path length without changing the fundamental two-dimensional layer structure.
Solution Approach 2:
The patent changes the optical parameters by introducing plasmonic structures with specific geometric parameters (height: 100-250 nm, width: 20-80 nm, pitch: 100-300 nm). These parameter changes enable localized surface plasmon resonance at specific wavelengths, transforming the optical interaction from simple absorption to resonance-enhanced diffraction and absorption.
2Quantity of substance
If the height of unit structures in the plasmonic structure portion is increased to enhance light diffraction, then localized surface plasmon resonance is improved, but the structure becomes more complex and difficult to manufacture
Solution Approach 1:
The patent optimizes the height parameter of the unit structures to a specific range (100-250 nm) that balances plasmonic resonance performance with manufacturability. This parameter optimization ensures that the structures are tall enough to generate effective localized surface plasmon resonance but not so tall as to create excessive aspect ratios that would be difficult to manufacture with standard semiconductor fabrication processes.
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 proposed design effectively increases the optical path length in the p-type semiconductor region, leading to improved light absorption and enhanced quantum efficiency.
Implementation Method 1
a plasmonic structure portion formed on the light incidence surface to diffract the light by surface plasmon resonance
Implementation Method 2
since localized surface plasmon resonance can occur in the plasmonic structure portion, incident light can be diffracted appropriately
Implementation Method 3
an avalanche photodiode including a light incidence surface on which light is incident
Data Source
AI summary
A photodetector includes an avalanche photodiode having a light incidence surface on which light is incident, and a plasmonic structure diffracting the light by surface plasmon resonance. An avalanche photodiode has a p-type first semiconductor region and an n-type second semiconductor region formed on a side of the first semiconductor region opposite to the light incidence surface to form a pn junction with the first semiconductor region. A plasmonic structure portion has a plurality of unit structures arranged on the first semiconductor region. Each of the plurality of unit structures has a top surface on a side opposite to the light incidence surface, a bottom surface facing the light incidence surface, and a side surface connected to the top surface and the bottom surface. The height of each of the plurality of unit structures is 100 nm or more and 250 nm or less.