Chalcogen-Doped Silicon Diode for 1.55 um Detection
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Solution Overview
Problem
Conventional silicon photodiodes are limited in detecting light beyond 1.1 um in wavelength due to silicon's absorption characteristics, and doping with chalcogens increases defect density, leading to high dark count rates.
Innovation Solution
A diode device with a doped silicon region containing chalcogens like selenium, tellurium, or sulfur, separated from the p-n junction by an epitaxial layer, allowing absorption of light up to 1.55 um while maintaining a low dark count rate through isolation of the generation and avalanche regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If silicon is doped with chalcogens to extend detection wavelength beyond 1.1 um, then light absorption capability is improved, but defect density increases leading to high dark count rates
Solution Approach 1:
The device is divided into functionally distinct regions: a first semiconductor region containing chalcogen-doped silicon for light absorption, and a second semiconductor region for avalanche multiplication. This segmentation allows each region to be optimized independently - the first region for extended wavelength detection and the second region for low-noise signal amplification.
Solution Approach 2:
An epitaxial region acts as an intermediary layer between the chalcogen-doped first semiconductor region and the second semiconductor region. This intermediate structure isolates the defect-prone doped region from the avalanche region, preventing defect-induced noise from propagating to the detection output while maintaining the extended wavelength detection capability.
2Adaptability or versatility
If chalcogen doping is applied to silicon to enable mid-infrared detection, then absorption of long wavelength light is improved, but manufacturing precision is compromised due to increased defect density
Solution Approach 1:
The semiconductor structure is segmented into a first region containing the chalcogen-doped silicon and a second region free from such doping. This allows the doped region to provide extended wavelength absorption while the undoped or lightly-doped second region maintains high manufacturing precision and low defect density for reliable avalanche operation.
Solution Approach 2:
Chalcogen doping is applied locally only in the first semiconductor region where it is needed for extending the absorption spectrum. The second semiconductor region maintains high purity and uniform quality, ensuring low defect density and high manufacturing precision in the critical avalanche multiplication zone.
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
Enables detection of light with wavelengths up to 1.55 um while keeping dark count rates low by isolating the doped silicon region from the p-n junction, effectively extending the detection range without significantly increasing defect-induced noise.
Implementation Method 1
capable of absorbing light waves having a wavelength of more than 1.1 um
Implementation Method 2
generating an electrical signal in response to very low intensity of light, such as even a single photon
Implementation Method 3
single photon avalanche photodiode (SPAD)
Data Source
AI summary
According to various embodiments, there is provided a diode device including a semiconductor substrate of a first conductivity type, a first semiconductor region formed within the semiconductor substrate, an epitaxial region of the first conductivity type, and a second semiconductor region of a second conductivity type different from the first conductivity type. The first semiconductor region includes a chalcogen. The epitaxial region is formed over the first semiconductor region. The second semiconductor region is formed over the epitaxial region.