Semiconductor Structure with Absorbing Region in Focusing Cavity
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Solution Overview
Problem
Semiconductor structures used for detecting electromagnetic radiation suffer from a non-zero dark current, which degrades the signal-to-noise ratio, especially in infrared wavelengths due to the low forbidden band width of the material, leading to significant noise and reduced absorption of radiation.
Innovation Solution
A semiconductor structure with a first and second semiconductor zone forming a junction, where the second zone has a portion with a concentration of majority carriers at least ten times lower than the first zone, arranged in a Fabry-Pérot type cavity to focus electromagnetic radiation, reducing dark current and enhancing absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the active zone occupies a large volume to maximize signal absorption, then the absorption of electromagnetic radiation is improved, but the dark current increases significantly degrading the signal-to-noise ratio
Solution Approach 1:
The invention segments the semiconductor structure into distinct zones: a first zone with high majority carrier concentration and a second zone with low majority carrier concentration. This segmentation allows the structure to benefit from both high absorption (in the first zone) and low dark current (in the second zone), resolving the contradiction between signal absorption and noise reduction
Solution Approach 2:
The invention applies local quality by creating a specific region (the second zone) with fundamentally different electrical properties (low majority carrier concentration) compared to the rest of the structure. This localized change in quality enables reduced dark current generation precisely where needed, while maintaining effective absorption in other regions
2Object-generated harmful factors
If a Fabry-Pérot cavity is used to concentrate electromagnetic radiation in a reduced zone, then the dark current is reduced, but the thickness of the active zone is reduced limiting radiation absorption
Solution Approach 1:
The invention resolves the thickness limitation by transitioning to a lateral configuration where the first and second zones are arranged side-by-side rather than stacked vertically. This dimensional change allows the structure to maintain a thin profile suitable for Fabry-Pérot cavity operation while providing sufficient total absorption path length through the lateral arrangement of multiple zones
3Object-generated harmful factors
If the thickness of the semiconductor layer is reduced to match the Fabry-Pérot cavity concentration zone, then the dark current is reduced, but the absorption rate of electromagnetic radiation decreases
Solution Approach 1:
The invention segments the absorption function across multiple zones (first zone with high carrier concentration and second zone with low carrier concentration) arranged laterally. This segmentation allows each zone to contribute to absorption while maintaining the thin overall structure required for effective Fabry-Pérot cavity operation, thus preserving absorption rate while reducing dark current
Solution Approach 2:
The invention changes the carrier concentration parameter across different zones rather than uniformly throughout the structure. By creating regions with different carrier concentrations, the structure achieves both low dark current (in low-concentration zones) and effective absorption (in high-concentration zones) within a thin overall profile
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 improves the signal-to-noise ratio and allows for increased sensitivity and reproducible calibration by reducing electron-hole pair recombinations and extending the operating temperature, while maintaining effective radiation absorption.
Implementation Method 1
a first cavity adapted to focus in the first cavity a part of the received electromagnetic field
Implementation Method 2
when a photon, having an energy greater than that of the forbidden band of the semiconductor material, penetrates the semiconductor junction, that -this will generate an electron-hole pair
Data Source
Figure 1
Figure 2~3
Figure 4a~4c
AI summary
The invention relates to a semiconductor structure (10) intended to receive an electromagnetic radiation (2), comprising: a first semiconductor area having a first type of conductivity (121), a second semiconductor area (122) having a second type of conductivity that is the opposite of the first type of conductivity, the second area being in contact with the first area such as to form a semiconductor junction. The second area has a portion having the concentration of majority carriers that is at least ten times lower than the concentration of majority carriers of the first area. The second area and the portion thereof are essentially provided in a first cavity (130) suitable for focusing at least part of the electromagnetic radiation in the first cavity. The invention further relates to a method for manufacturing such a structure and a semiconductor component.