Optical Waveguide Photodetector Uniform Depletion
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Solution Overview
Problem
Optical waveguide type photodetectors with integrated optical waveguide and waveguide type photodiode structures on a common substrate face challenges in achieving uniform depletion ranges due to inclined butt joint interfaces, leading to increased maximum electric fields and edge breakdown.
Innovation Solution
Incorporating a multiplication layer and an electric field lowering layer between the semiconductor layer and the optical absorption layer, extending throughout the optical waveguide structure, to ensure uniform depletion ranges and reduce maximum electric fields, thereby preventing edge breakdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an inclined butt joint interface is formed between optical waveguide and photodiode regions, then coupling efficiency is improved, but depletion range uniformity deteriorates and maximum electric field increases
Solution Approach 1:
The patent segments the semiconductor structure into distinct functional regions: an optical waveguide region with an inclined end face for coupling, and a photodiode region with a vertical end face for detection. This segmentation allows each region to be optimized independently - the waveguide region achieves high coupling efficiency through the inclined interface, while the photodiode region maintains uniform depletion through its vertical structure, thereby resolving the contradiction between coupling efficiency and depletion uniformity.
2Ease of manufacture
If an inclined butt joint interface is used for coupling, then optical coupling is enhanced, but edge breakdown risk increases due to increased maximum electric field
Solution Approach 1:
The patent divides the device into separate optical waveguide and photodiode regions with different end face geometries. The waveguide region uses an inclined end face optimized for optical coupling, while the photodiode region uses a vertical end face that prevents edge breakdown. This spatial segmentation allows the system to achieve high optical coupling without suffering from the edge breakdown problems that would occur if the entire structure used an inclined interface.
3Device complexity
If the photodiode and waveguide structures are integrated on a common substrate, then manufacturing complexity is reduced, but achieving uniform depletion becomes more difficult
Solution Approach 1:
The patent integrates the photodiode and waveguide structures on a common semiconductor substrate while segmenting their end face geometries. The photodiode region is formed with a vertical end face to ensure uniform depletion, while the waveguide region is formed with an inclined end face for optimal coupling. This segmented approach within an integrated structure allows both manufacturing simplicity and precise control over depletion characteristics.
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 uniform depletion ranges across the multiplication layer, reducing the likelihood of edge breakdown and enhancing the reliability and sensitivity of the photodetector, while simplifying manufacturing by allowing the layers to grow on the entire semiconductor surface.
Implementation Method 1
an optical waveguide structure (80)... includes an optical waveguiding core layer (81) and a cladding layer (82)
Implementation Method 2
a waveguide type photodiode structure (19)... includes an optical absorption layer (13)
Data Source
AI summary
An optical waveguide type photodetector includes a first semiconductor layer of a first conductive type, a multiplication layer of a first conductive type on the first semiconductor layer, an optical waveguide structure, and a photodiode structure. The photodiode structure has a third semiconductor layer of a second conductive type, an optical absorption layer of an intrinsic conductive type or of a second conductive type, and a second semiconductor layer of a second conductive type. The optical waveguide structure includes an optical waveguiding core layer and a cladding layer. An end face of the photodiode structure located in a second region of the first semiconductor layer and an end face of the optical waveguide structure located in a first region of the first semiconductor layer are in contact.