Faceted Photodiode Absorption Region for Breakdown Suppression
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Solution Overview
Problem
Reducing the size of photodiodes to increase speed can lead to junction breakdown and dark current spikes due to the proximity of oppositely doped regions.
Innovation Solution
A photodiode design with an absorption region that includes a base region and facet regions with tapered surfaces, creating additional physical separation between the silicon cap and the doped layer, reducing the risk of junction breakdown and dark current spikes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the size of photodiodes is reduced to increase speed, then the speed is improved, but junction breakdown and dark current spikes occur due to the proximity of oppositely doped regions
Solution Approach 1:
The absorption region transitions from a planar structure to a three-dimensional structure with tapered surfaces and step regions. This vertical dimensionality change creates additional separation distance between the silicon cap and the doped layer, preventing junction breakdown while maintaining the compact lateral footprint needed for high-speed operation
Solution Approach 2:
The absorption region acts as an intermediary structure between the silicon cap and the doped layer. By positioning this absorption region with its base on the doped layer and extending upward with tapered surfaces, it mediates the spatial relationship between the oppositely doped regions, ensuring adequate separation distance is maintained
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 physical separation between the cap and the doped layer, reducing the likelihood of junction breakdown and dark current spikes while maintaining high photodiode speed.
Implementation Method 1
The photodiodes convert optical signals into electrical signals. The photodiodes may include an absorption region through which optical signals pass. The optical signals separate electrical carriers in the absorption region, generating electrical signals.
Data Source
AI summary
The present disclosure relates to a photodiode and method of forming the photodiode. The photodiode includes a doped layer and an absorption region positioned on the doped layer. The absorption region includes a base region contacting the doped layer, a first facet region positioned on the base region, and a second facet region positioned on the first facet region. The first facet region includes (i) a first tapered surface and a second tapered surface extending from the base region and (ii) a first step region and a second step region extending laterally from the first tapered surface and the second tapered surface, respectively. The second facet region includes a third tapered surface extending from the first step region and a fourth tapered surface extending from the second step region.