Germanium Photodetector With Silicon Nitride Waveguide Coupling
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Solution Overview
Problem
Current germanium-silicon photoelectric detectors suffer from low responsivity and an inability to handle high light power detection due to nonlinear effects, saturable absorption, and propagation losses in silicon slab waveguides, which limit their effectiveness in optical communication.
Innovation Solution
A photoelectric detector design featuring a silicon nitride waveguide arranged around a germanium layer, with a silicon dioxide material in between, to enhance optical signal coupling and reduce saturation, while maintaining low nonlinearity and supporting high optical power density, thereby improving responsivity without increasing the length of the coupling region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a silicon slab waveguide is used to transmit optical signals, then the device can be integrated with CMOS technology, but nonlinear effects and saturable absorption occur at high optical power densities
Solution Approach 1:
The patent introduces a silicon nitride waveguide as an intermediary component to transmit optical signals, replacing the problematic silicon slab waveguide. The silicon nitride material has lower nonlinear refractive index and does not exhibit saturable absorption at high optical power densities, thereby mediating between the need for integration and the avoidance of nonlinear effects
Solution Approach 2:
The patent employs a composite structure combining silicon nitride waveguide with germanium layer. The silicon nitride provides low-nonlinear optical transmission, while the germanium layer provides efficient photoelectric detection. This composite approach allows the system to benefit from both materials' advantages without suffering from silicon's high optical power limitations
2Measurement precision
If the coupling region length is increased to improve responsivity, then more optical power can be detected, but propagation loss increases
Solution Approach 1:
The patent changes the material parameter of the waveguide from silicon to silicon nitride. This parameter change fundamentally alters the propagation characteristics, reducing both nonlinear effects and propagation loss. As a result, the coupling region can be optimized for high responsivity without suffering from excessive propagation losses that would occur with longer coupling lengths in silicon-based waveguides
3Measurement precision
If germanium material is used for light absorption, then detection efficiency in optical communication band improves, but incompatibility with silicon technology prevents monolithic integration
Solution Approach 1:
The patent segments the device into distinct functional regions: a silicon nitride waveguide region for optical signal transmission and a germanium layer region for photoelectric detection. This segmentation allows each component to be optimized for its specific function while being fabricated on a common silicon substrate, achieving both high detection efficiency and compatibility with silicon-based manufacturing 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 solution enables high optical power detection with reduced propagation loss and saturation absorption, enhancing the detector's responsivity and bandwidth without extending the coupling region, thus addressing the limitations of existing germanium-silicon detectors.
Implementation Method 1
a silicon nitride waveguide arranged around a germanium layer in extension directions of at least three sidewalls of the germanium layer
Implementation Method 2
The silicon nitride waveguide is configured to transmit an optical signal and couple the optical signal to the Ge layer
Implementation Method 3
the Ge layer is configured to detect the optical signal and convert the optical signal into an electrical signal
Data Source
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AI summary
Provided is a photoelectric detector, comprising: a silicon layer (110), the silicon layer (110) comprising a first-doping-type doped region (111); a germanium layer (120) in contact with the silicon layer (110), the germanium layer (120) comprising a second-doping-type doped region (121); and a silicon nitride waveguide (130), the silicon nitride wavegnide (130) being arranged surrounding the germanium layer (120) along the extension directions of at least three side walls of the germanium layer (120), wherein the silicon nitride waveguide (130) is used for transmitting an optical signal and coupling the optical signal to the germanium layer (120), and the germanium layer (120) is used for detecting the optical signal and converting the optical signal into an electrical signal.