Non-diffusion Photodiode Boundary Design for Dark Current Reduction
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Solution Overview
Problem
Non-diffusion type photodiodes generate a relatively large dark current, which hinders their application in various industries compared to conventional avalanche photodiodes.
Innovation Solution
A non-diffusion type photodiode structure is defined with a specific boundary relationship between an intermediate layer and a multiplication/window layer, where the intermediate layer is an I-type semiconductor or graded refractive index layer, and the multiplication/window layer is positioned such that the distance between their boundaries is greater than or equal to 1 micron, reducing dark current generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a non-diffusion type photodiode is used to simplify manufacturing processes, then manufacturing complexity is reduced, but dark current increases significantly
Solution Approach 1:
The photodiode is divided into distinct functional layers with clearly defined boundaries. The intermediate layer is segmented to create a specific boundary relationship with the multiplication/window layer, where the intermediate layer's first boundary surrounds the multiplication/window layer's second boundary with a controlled distance of 1-15 micrometers. This segmentation isolates the multiplication/window layer from direct contact with other layers, reducing dark current generation while maintaining the non-diffusion manufacturing advantage.
2Productivity
If the multiplication/window layer is directly formed without diffusion, then manufacturing steps are reduced, but dark current generation increases
Solution Approach 1:
An intermediate layer is introduced as a mediator between the light absorption layer and the multiplication/window layer. This intermediate layer acts as a buffer that reduces dark current generation by preventing direct interaction between carriers and the multiplication/window layer interface. The intermediate layer maintains the non-diffusion manufacturing approach while providing the necessary isolation to reduce harmful dark current effects.
3Area of stationary object
If the boundary distance between intermediate layer and multiplication/window layer is reduced, then device area is minimized, but dark current increases
Solution Approach 1:
The boundary distance between the intermediate layer and multiplication/window layer is optimized to a specific parameter range of 1-15 micrometers. This parameter change balances the competing requirements of minimizing device area while maintaining sufficient separation to reduce dark current. The graded refractive index of the intermediate layer further optimizes this parameter relationship by controlling light propagation and carrier distribution in the critical boundary region.
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
This configuration significantly reduces dark current by up to 99.8% compared to conventional designs, improving the photodiode's performance and applicability.
Implementation Method 1
The intermediate layer is an I-type semiconductor layer or a graded refractive index layer
Implementation Method 2
a non-diffusion type photodiode which reduces generation of dark current
Implementation Method 3
an avalanche photodiode used in optical communication is also provided with a multiplication/window layer
Data Source
AI summary
A non-diffusion type photodiode is described and has: a substrate, a buffer layer, a light absorption layer, an intermediate layer, and a multiplication/window layer. The buffer layer is disposed on the substrate. The light absorption layer is disposed on the buffer layer. The intermediate layer is disposed on the light absorption layer and has a first boundary, wherein the intermediate layer is an I-type semiconductor layer or a graded refractive index layer. The multiplication/window layer is disposed on the intermediate layer and has a second boundary, wherein in a top view, the first boundary surrounds the second boundary, and a distance between the first boundary and the second boundary is greater than or equal to 1 micrometer. The non-diffusion type photodiode can reduce generation of dark current.