Semiconductor Photodetector Diffraction Grating Light Absorption
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor photodetectors face challenges in achieving high light absorption efficiency and response speed due to the trade-off between absorption layer thickness and carrier travel distance, leading to delayed electric current components and reduced modulation speed.
Innovation Solution
Incorporating a diffraction grating layer that surrounds the region below the light transmissive layers to diffract light, increasing absorption within the depletion layer and reducing the distance carriers need to travel, thereby enhancing light absorption efficiency and response speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the thickness of the light absorption layer is increased to improve light absorption efficiency, then the light absorption efficiency is improved, but the response speed is reduced due to increased carrier travel distance
Solution Approach 1:
The patent introduces a diffraction grating layer that redirects light propagation from a vertical path to an oblique path, effectively increasing the interaction length between light and the absorption layer without increasing the physical thickness. This dimensional change in light propagation allows carriers to be generated closer to the depletion layer while still maintaining high absorption efficiency.
Solution Approach 2:
The diffraction grating layer acts as an intermediary structure between the incident light and the light absorption layer. It modifies the light path by diffracting incident light at oblique angles, thereby enabling more efficient light absorption in a thinner layer and reducing the distance carriers must travel to reach the depletion layer.
2Use of energy by stationary object
If the distance between top electrode and bottom electrode is decreased to reduce power consumption, then the power consumption is reduced, but the light absorption efficiency may be compromised
Solution Approach 1:
By changing the light propagation dimension from vertical to oblique through the diffraction grating, the patent enables effective light absorption in a compressed vertical space, allowing reduced electrode distance while maintaining absorption efficiency.
Solution Approach 2:
The patent changes the optical path parameters by introducing diffraction, which allows the light to interact more effectively with the absorption layer within a shorter vertical distance, thereby enabling reduced device thickness and lower power consumption without sacrificing absorption efficiency.
3Quantity of substance
If carriers are generated in regions away from the depletion layer to increase light absorption, then the light absorption efficiency is improved, but delayed current components increase reducing response speed
Solution Approach 1:
The diffraction grating changes the spatial distribution of carrier generation by redirecting light to propagate obliquely through the absorption layer, concentrating carrier generation events closer to the depletion layer region and reducing the distance carriers must travel.
Solution Approach 2:
The diffraction grating layer serves as an intermediary that controls where and how light interacts with the absorption layer, ensuring that carrier generation is concentrated in regions closer to the depletion layer, thereby reducing delayed current components while maintaining overall absorption 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
The diffraction grating layer increases light absorption efficiency by directing more light into the depletion layer and reduces delayed current components, resulting in improved response speed and efficiency in converting incident light to electric current.
Implementation Method 1
a diffraction grating layer formed on the light absorption layer and including a diffraction grating for diffracting light
Implementation Method 2
the light incident through the light receiving surface of the semiconductor photodetector is absorbed by its light absorption layer, which is a region with a narrow energy band, resulting in the generation of carriers within the absorption layer
Data Source
AI summary
A semiconductor photodetector includes a semiconductor substrate of a first conductivity type, a light absorption layer of the first conductivity type on the semiconductor substrate and absorbing light, a diffraction grating layer on the light absorption layer and including a diffraction grating diffracting light, a first light transmissive layer of a second conductivity type on the diffraction grating layer and transmitting light, and a second light transmissive layer of the first conductivity type on the diffraction grating layer and surrounding the first light transmissive layer, the second light transmissive layer transmitting light. The diffraction grating surrounds a region of the diffraction grating layer that is directly below the first light transmissive layer.