Silicon Heterojunction Pixel Architecture for CMOS-Compatible LWIR Detection
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Solution Overview
Problem
Current infrared (IR) detection and imaging technologies are hindered by high costs and complex fabrication processes, making them unsuitable for mass production and integration with CMOS-compatible systems, which limits their application in cost-effective and high-temperature operation for IR cameras.
Innovation Solution
The development of pixel architectures for photodetector systems using a silicon substrate with dielectric layers and a heterojunction formed by epitaxially extending Group IVA semiconductor alloys, allowing for the absorption of visible and infrared radiation, including short-wave, mid-wave, and long-wave infrared, with a focus on reducing manufacturing costs and enabling CMOS-compatible growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If narrow gap III-V alloys (InGaAs, InSb) or IV-VI (PbSnTe, PbS) or II-VI (HgCdTe) material systems are used for IR detection, then bandgap engineering capability and IR detection performance are improved, but manufacturing cost increases, fabrication complexity increases, and operating temperature decreases
Solution Approach 1:
The patent changes the material composition parameters by using Group IVA semiconductor alloys (SiGe, GeSn) with varying Ge and Sn content to achieve different bandgaps for SWIR, MWIR, and LWIR detection. This allows tuning of detection wavelengths while maintaining CMOS compatibility, resolving the contradiction between performance and manufacturability
Solution Approach 2:
The patent employs composite heterostructure materials combining SiGe and GeSn alloys in a vertical stack, where each layer has optimized composition for specific wavelength ranges. This composite approach enables multi-spectral detection while using CMOS-compatible materials, addressing both performance and manufacturing concerns
2Reliability
If hybrid integration of III-Vs or II-Vs on Si substrate is implemented, then IR detection capability is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent makes the Si-based platform universal by demonstrating that the same heterostructure approach can detect SWIR, MWIR, and LWIR by simply adjusting alloy composition, eliminating the need for different material systems for different wavelength ranges and simplifying manufacturing
Solution Approach 2:
The patent replaces expensive, difficult-to-fabricate III-V and II-VI materials with cheaper, CMOS-compatible SiGe and GeSn alloys that can be grown using standard semiconductor fabrication processes, significantly reducing manufacturing cost and complexity
3Reliability
If mature IR detection technology is used, then detection performance is improved, but operating temperature decreases and manufacturing cost increases
Solution Approach 1:
The patent changes the bandgap parameter through controlled Ge and Sn alloy composition to achieve high-temperature operation. By optimizing the alloy content, the material maintains appropriate bandgap for IR detection while enabling operation at higher temperatures than traditional cooled IR detectors
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 approach enables the creation of cost-effective, high-temperature IR camera systems suitable for mass production, with reduced manufacturing costs and improved performance, allowing for efficient detection of infrared radiation across various spectral ranges.
Implementation Method 1
the photoactive region can absorb electromagnetic radiation selected from the group consisting of short-wave infrared radiation (SWIR), mid-wave infrared radiation (MWIR), and long-wave infrared radiation (LWIR)
Implementation Method 2
The first Group IVA semiconductor alloy can have a bandgap larger than the second Group IVA semiconductor alloy... the photoactive region, in some embodiments, can absorb infrared radiation having a wavelength up to 15 μm, up to 10 μm, or up to 5 μm
Data Source
AI summary
In one aspect, pixel architectures for employment in photodetector apparatus and systems are described herein. A pixel, in some embodiments, comprises a silicon substrate, and one more dielectric layers over the substrate. The dielectric layers, for example, can comprise silica (SiO2) and/or other suitable dielectric material(s). A photoactive region resides within the one or more dielectric layers, the photoactive region comprising a heterojunction formed of a first Group IVA semiconductor alloy epitaxially extending from an aperture passing through the one or more dielectric layers to the silicon substrate, and a second Group IVA semiconductor alloy extending epitaxially from the first Group IVA semiconductor alloy.