Two-Dimensional APD and SPAD Lateral Multiplication
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Solution Overview
Problem
Existing avalanche photodiodes (APDs) and single photon avalanche detectors (SPADs) face design limitations due to the stacked configuration of semiconductor layers, which can degrade performance when attempting to improve one layer's operation.
Innovation Solution
The development of two-dimensional APDs and SPADs with a germanium absorption layer over a silicon surface layer, where the multiplication region is laterally adjacent and separate from the absorption layer, allowing for independent optimization of photon absorption and amplification, and incorporating an integrated quenching region to control photocurrent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a stacked configuration of semiconductor layers is used in APDs and SPADs, then the device structure is simplified and manufacturing is easier, but the performance of the device degrades when attempting to improve one layer's operation
Solution Approach 1:
The patent transitions from a traditional one-dimensional stacked configuration to a two-dimensional planar configuration where the absorption layer and multiplication region are arranged side-by-side rather than stacked vertically. This dimensional change allows independent optimization of each region's properties without the performance degradation that occurs in stacked structures when one layer is modified.
2Area of stationary object
If a traditional stacked configuration is used, then the device occupies less area, but the sensitivity and efficiency of photon detection are reduced
Solution Approach 1:
By arranging the absorption layer and multiplication region in a lateral, side-by-side configuration rather than stacking them vertically, the patent achieves improved photon detection sensitivity and efficiency while maintaining a compact footprint. The two-dimensional planar layout allows for larger active areas and better optical coupling without increasing the vertical profile significantly.
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 enhances the sensitivity and efficiency of the detectors by allowing independent optimization of absorption and amplification processes, improving the detection of low-power optical signals and reducing degrading effects, while maintaining compactness and high bandwidth-power product.
Implementation Method 1
a germanium absorption layer, disposed over a charge region of a silicon surface layer, to receive and absorb photons from the optical signal, and to generate one or more mobile carriers from the absorbed photons
Implementation Method 2
a multiplication region, laterally adjacent to the charge region, to receive the one or more mobile carriers and generate an amplified photocurrent
Implementation Method 3
an optical waveguide configured to transport an optical signal; an optical waveguide that is positioned with respect to a germanium absorption layer so as to couple an optical signal transported by the waveguide to the germanium absorption layer
Data Source
AI summary
Avalanche photodiodes (APDs) and single photon avalanche detectors (SPADs) are provided with a lateral multiplication region that provides improved amplification through increased impact ionization.