Lateral Avalanche Photodetector Layout for Uniform Field and Carrier Transport
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Solution Overview
Problem
Current avalanche photodetectors face issues with uneven electric field distribution in the absorption region and unideal gain bandwidth product, leading to decreased responsiveness and efficiency in optical communication.
Innovation Solution
A laterally structured avalanche photodetector is designed with a substrate, a first epitaxial growth layer, and a second epitaxial growth layer, where the epitaxial growth layers are formed with different semiconductor materials to create a more uniform electric field distribution and enhance the gain bandwidth product, with the absorption region and avalanche region arranged in a specific configuration to improve photogenerated carrier transport.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional avalanche photodetector structure is used, then manufacturing is simpler, but electric field distribution in absorption region is uneven
Solution Approach 1:
The patent transitions from a conventional vertical stacking structure to a lateral structure where the absorption region and avalanche region are arranged side-by-side in the horizontal plane. This dimensional reconfiguration allows the electric field to be more uniformly distributed across the absorption region while maintaining functional separation between carrier generation and multiplication zones.
Solution Approach 2:
The patent introduces distinct doping regions (P-type and N-type) positioned at specific locations to create localized electric field control. The P-type doping region and N-type doping region are strategically placed to generate electric fields that uniformly distribute across the absorption region, addressing the local quality needs of different functional zones within the device.
2Productivity
If conventional photodetector structure is used, then device complexity is lower, but gain bandwidth product is unideal
Solution Approach 1:
The patent divides the photodetector into distinct epitaxial growth layers with specific functions: a first epitaxial growth layer containing the absorption region, a second epitaxial growth layer containing the avalanche region, and a third epitaxial growth layer containing charge regions. This segmentation allows each layer to be optimized for its specific function, thereby improving the gain bandwidth product.
Solution Approach 2:
By arranging the absorption region and avalanche region laterally rather than vertically, the patent enables simultaneous optimization of both regions without the trade-offs inherent in vertical stacking. This lateral arrangement allows independent optimization of absorption efficiency and avalanche gain, leading to an improved gain bandwidth product.
3Productivity
If absorption region and avalanche region are vertically stacked, then manufacturing is easier, but photogenerated carrier transport is less efficient
Solution Approach 1:
The patent arranges the absorption region and avalanche region side-by-side in the horizontal plane rather than stacking them vertically. This lateral configuration creates a direct path for photogenerated carriers to travel from the absorption region to the avalanche region, significantly improving carrier transport efficiency by eliminating vertical transport bottlenecks.
Solution Approach 2:
The patent introduces charge regions (P-type and N-type doping regions) that act as intermediaries to facilitate carrier transport between the absorption region and avalanche region. These charge regions create electric fields that actively drive carriers across the lateral distance, enhancing transport efficiency beyond what passive diffusion could achieve.
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 achieves a more uniform electric field distribution, enhances photogenerated carrier transport, and improves the gain bandwidth product, reducing dark current and increasing the quantum efficiency of the photodetector.
Implementation Method 1
The first epitaxial growth layer... has an upper surface used as an optical absorption surface... and the absorption region and the avalanche region are arranged at an interval along a first direction
Implementation Method 2
an avalanche region of the avalanche photodetector is formed... the first charge region, the absorption region, the second charge region and the avalanche region at least partially overlap in the first direction
Data Source
AI summary
A laterally structured avalanche photodetector and a manufacturing method therefor. The laterally structured avalanche photodetector comprises: a substrate, comprising a first semiconductor material region (103), an avalanche region (115) being formed in the first semiconductor material region (103); a first epitaxial growth layer (120), formed as an absorption region (180), the upper surface of the first epitaxial growth layer (120) being a light absorption surface and protruding from the upper surface of the first semiconductor material region (103), and the lower surface of the first epitaxial growth layer (120) being lower than the upper surface of the first semiconductor material region (103); and a second epitaxial growth layer (130), at least comprising a first portion and a second portion which are located at two sides of the first epitaxial growth layer (120) in a first direction, the first portion and the second portion respectively covering two side walls of the first epitaxial growth layer (120) protruding above the first semiconductor material region (103), the first portion and the second portion being respectively formed as at least a part of a first charge region (113) and at least a part of a second charge region (114), and the first charge region (113), the absorption region (180), the second charge region (114) and the avalanche region (115) at least partially overlapping in the first direction.