Three-Terminal Avalanche Photodiode With Independent Field Control
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Solution Overview
Problem
Traditional avalanche photodiodes (APDs) face challenges with high breakdown voltage, large size, high power consumption, and low quantum efficiency, making them unsuitable for on-chip optical interconnect applications, and require complex fabrication processes due to precise doping control.
Innovation Solution
A novel APD design utilizing three terminals for low breakdown voltage and resonant enhancement, allowing independent control of absorption and multiplication regions' electric fields, eliminating the need for separate absorption charge multiplication (SACM) design and precise doping, and compatible with CMOS fabrication techniques, achieving small size, low power consumption, and high quantum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate absorption charge multiplication (SACM) design is used, then avalanche multiplication is achieved, but breakdown voltage becomes very high (>25V)
Solution Approach 1:
The patent combines the absorption region and multiplication region into a single integrated structure where both functions occur in the same physical region. This merging eliminates the need for separate SACM design, reducing the breakdown voltage from >25V to a much lower level while maintaining avalanche multiplication capability through the unified region design.
Solution Approach 2:
The patent applies local quality by creating regions with different doping concentrations within the same structure - heavily doped regions for multiplication and lightly doped regions for absorption. This localized variation in doping quality enables the single region to perform both absorption and multiplication functions at low breakdown voltage.
2Reliability
If long absorption length is used for materials with lower absorption efficiency, then quantum efficiency is improved, but device size becomes large and bulky
Solution Approach 1:
The patent changes the doping concentration parameter within the absorption region to create a gradient or varied doping profile. This parameter change enhances the absorption coefficient, allowing sufficient quantum efficiency to be achieved with a shorter absorption length, thereby reducing the overall device size while maintaining high quantum efficiency.
3Reliability
If precise doping control is implemented to define and control layers, then structure viability is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent segments the device into distinct functional regions (absorption region and multiplication region) with different doping concentrations. This segmentation allows each region to be optimized independently for its specific function while using standard fabrication techniques, reducing the need for complex precise doping control across the entire structure and simplifying the manufacturing process.
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 achieves high quantum efficiency, low dark current, and low power consumption with operational voltages of approximately 5-12 volts, suitable for on-chip optical interconnects and other high-bandwidth applications, while avoiding the complexities of traditional APD structures.
Implementation Method 1
an absorption region disposed on the multiplication region and associated with a third terminal, wherein the absorption region is to absorb photons and generate electrical carriers
Implementation Method 2
a multiplication region associated with a second terminal and separated from the first region by the multiplication region, wherein the multiplication region is to avalanche multiply the generated carriers
Data Source
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AI summary
A device includes a first region, a multiplication region, a second region, and an absorption region. The first region is associated with a first terminal, and the second region is associated with a second terminal. The first region is separated from the second region by the multiplication region. The absorption region is disposed on the multiplication region and associated with a third terminal. A multiplication region electric field is independently controllable with respect to an absorption region electric field, based on the first terminal, the second terminal, and the third terminal.