Photodetector Heterointerface Doping 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 their sensitivity and signal-to-noise ratio.
Innovation Solution
A photodetector apparatus is designed with a heterointerface between a substrate and an absorption region, where the substrate has a lower doping concentration than the absorption region, and a carrier conducting layer with a different material, optimizing doping concentrations to reduce dark current and increase quantum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the substrate has a high doping concentration to improve carrier conductivity, then the electrical conductivity is improved, but the dark current increases
Solution Approach 1:
The device is segmented into distinct regions with different doping concentrations: a first doped region in the substrate with higher doping concentration for conductivity, and a second doped region at the heterointerface with lower doping concentration to suppress dark current. This spatial segmentation allows each region to optimize for its specific function.
Solution Approach 2:
Different regions of the device are assigned different local properties: the substrate region has high doping concentration for carrier supply, while the heterointerface region has low doping concentration for dark current suppression. This local quality differentiation resolves the contradiction between conductivity and dark current.
2Productivity
If the absorption region has a high doping concentration to improve carrier generation, then the quantum efficiency is improved, but the dark current increases
Solution Approach 1:
The doping structure is segmented such that the absorption region benefits from the substrate's high doping concentration for carrier generation, while the heterointerface region maintains low doping concentration to suppress dark current. The ratio of doping concentrations between these regions is controlled to be 10 or more.
Solution Approach 2:
The heterointerface region acts as an intermediary between the high-doped substrate and the absorption region, mediating the trade-off by providing a low-doping zone that suppresses dark current while allowing the absorption region to maintain high quantum efficiency.
3Productivity
If a heterointerface is formed between different materials to enhance optical absorption, then the quantum efficiency is improved, but interface defects increase dark current
Solution Approach 1:
The doping concentration parameter is changed across the heterointerface, with the interface region having a doping concentration at least 10 times lower than the substrate. This parameter change suppresses dark current generation at the interface while maintaining the material composition needed for optical absorption.
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 solution achieves significantly lower dark current and higher quantum efficiency by leveraging the doping concentration ratio and material differences at the heterointerface, improving the overall performance of the photodetector.
Implementation Method 1
an absorption region in contact with the carrier conducting layer and configured to receive an optical signal and to generate photo-carriers in response to the optical signal
Data Source
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.