Heterointerface Photodetector Layout for Low Dark Current
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Solution Overview
Problem
Current photodetectors face challenges in reducing dark current and enhancing quantum efficiency due to limitations in doping concentration ratios and material interfaces, which affect signal-to-noise ratio and sensitivity.
Innovation Solution
A photodetector design featuring a substrate with a second dopant having a lower peak doping concentration than the absorption region, forming a heterointerface with a doping concentration ratio greater than 10, and a carrier conducting layer with a different material, reducing dark current and increasing quantum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the doping concentration in the absorption region is increased to improve quantum efficiency, then the quantum efficiency is improved, but the dark current increases
Solution Approach 1:
The patent applies local quality by creating distinct doping concentration zones: the absorption region has high doping concentration (≥1×10^16 atoms/cm³) for high quantum efficiency, while the carrier conducting layer has low doping concentration (≤1×10^15 atoms/cm³) for low dark current. This spatial differentiation of doping concentrations allows each region to optimize its local function without compromising the other.
Solution Approach 2:
The patent uses composite material structure by forming a heterointerface between the absorption region and carrier conducting layer made of different semiconductor materials (e.g., InGaAs absorption region with InP carrier conducting layer). This material composition difference, combined with the doping concentration ratio ≥10, creates effective potential barriers that suppress dark current while maintaining high carrier collection efficiency.
2Ease of manufacture
If a homointerface is used between absorption region and substrate, then the manufacturing is simplified, but the dark current is high due to interface defects
Solution Approach 1:
The patent replaces homointerfaces with heterointerfaces between dissimilar semiconductor materials (e.g., InGaAs/InP). This material discontinuity creates built-in potential barriers at the interface that effectively block dark current generation from interface defects, while the fabrication process remains compatible with standard semiconductor manufacturing techniques.
3Object-generated harmful factors
If the doping concentration ratio between absorption region and carrier conducting layer is less than 10, then the manufacturing precision is reduced, but the dark current reduction is insufficient
Solution Approach 1:
The patent establishes a specific parameter threshold (doping concentration ratio ≥10) as a design criterion. By setting the absorption region doping concentration at ≥1×10^16 atoms/cm³ and the carrier conducting layer doping concentration at ≤1×10^15 atoms/cm³, the patent ensures sufficient potential barrier height to suppress dark current, while this ratio provides a clear manufacturing target that balances performance requirements with fabrication capabilities.
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 significantly lower dark current and higher quantum efficiency by optimizing doping concentrations and material interfaces, leading to improved signal-to-noise ratio and sensitivity.
Implementation Method 1
a first light absorption region configured to absorb photons and to generate photo-carriers from the absorbed photons
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A photo-detecting apparatus is provided. The photo-detecting apparatus includes a carrier conducting layer having a first surface; an absorption region is doped with a first dopant having a first conductivity type and a first peak doping concentration, wherein the carrier conducting layer is doped with a second dopant having a second conductivity type and a second peak doping concentration, wherein the carrier conducting layer comprises a material different from a material of the absorption region, wherein the carrier conducting layer is in contact with the absorption region to form at least one heterointerface, wherein a ratio between the first peak doping concentration of the absorption region and the second peak doping concentration of the carrier conducting layer is equal to or greater than 10; and a first electrode and a second electrode both formed over the first surface of the carrier conducting layer.