Silicon Nitride–Germanium Photoelectric Detector for High-Power Detection
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Solution Overview
Problem
Conventional germanium-silicon photoelectric detectors suffer from low responsivity and incapability of high light power detection due to the energy band structure of crystalline silicon and the incompatibility of Group III-V semiconductor materials with silicon technology, leading to issues like two-photon absorption, saturable absorption, and propagation loss.
Innovation Solution
A photoelectric detector design incorporating a silicon nitride waveguide surrounding a germanium layer, which transmits and couples optical signals to the germanium layer for conversion into electrical signals, utilizing a silicon nitride material with low nonlinearity to avoid two-photon absorption and ensure high coupling efficiency, and a Ge layer for detection, with a PIN or NIP structure for charge carrier extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional germanium-silicon photoelectric detector is used, then the device structure is simple, but the responsivity is low and high light power detection capability is lost
Solution Approach 1:
The patent employs a composite structure combining silicon nitride waveguide and germanium absorption layer. The silicon nitride material provides low nonlinearity and low propagation loss, while the germanium layer provides high absorption efficiency. This composite approach resolves the contradiction by achieving high responsivity through material composition rather than simply increasing device size or complexity.
Solution Approach 2:
The silicon nitride waveguide acts as an intermediary between the optical signal source and the germanium absorption layer. It guides and couples light to the germanium layer with low loss, enabling efficient energy transfer without direct contact between the optical source and the detector, thus improving responsivity while maintaining manageable device complexity.
2Measurement precision
If the coupling region length is increased to improve responsivity, then the responsivity increases, but the propagation loss increases
Solution Approach 1:
The patent changes the material parameter of the waveguide from conventional silicon-based materials to silicon nitride, which has fundamentally different optical properties including lower nonlinear refractive index and lower propagation loss. This parameter change allows for longer coupling regions to be used without incurring excessive propagation loss, thereby improving responsivity while controlling energy loss.
Solution Approach 2:
The composite structure of silicon nitride waveguide and germanium absorption layer enables independent optimization of different functions: the silicon nitride portion minimizes propagation loss during light transmission, while the germanium portion maximizes absorption efficiency at the detection interface, resolving the contradiction between coupling length and propagation loss.
3Power
If high optical power is detected, then the detection capability is improved, but saturation absorption occurs
Solution Approach 1:
The patent utilizes the low nonlinear refractive index parameter of silicon nitride material to reduce optical nonlinear effects such as saturable absorption and two-photon absorption. This material parameter change enables the detector to handle high optical power levels without entering saturation regime, maintaining reliable detection across a wide dynamic range.
4Ease of manufacture
If silicon-based waveguide is used, then the manufacturing is easy, but two-photon absorption occurs reducing detection accuracy
Solution Approach 1:
The patent uses a composite structure where silicon nitride waveguide handles light transmission with minimal two-photon absorption, while germanium absorption layer performs the actual detection. This division of labor allows silicon nitride to provide low-loss transmission (improving detection accuracy) while the germanium layer maintains compatibility with CMOS fabrication processes (preserving ease of manufacture).
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 design enhances responsivity and supports high optical power detection without increasing the length of the coupling region, reducing propagation loss and avoiding saturation, while maintaining low-loss optical transmission with large optical bandwidth.
Implementation Method 1
a silicon nitride waveguide arranged around the Ge layer in extension directions of at least three sidewalls of the Ge layer. The silicon nitride waveguide is configured to transmit an optical signal and couple the optical signal to the Ge layer
Implementation Method 2
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
Implementation Method 4
a Silicon (Si) layer including a first-doping-type doped region; a Germanium (Ge) layer in contact with the Si layer and including a second-doping-type doped region
Data Source
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 waveguide (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.