Dual Wavelength Imaging Cell Array Using Quantum Dot Structures
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Solution Overview
Problem
Current semiconductor imaging technologies face limitations in efficiently detecting electromagnetic radiation across multiple wavelength bands due to the lack of effective mechanisms for lateral charge transfer and accumulation in imaging cells, leading to suboptimal performance in both single and dual-wavelength imaging applications.
Innovation Solution
The semiconductor device incorporates a modulation doped quantum well structure with a buried channel and self-assembled quantum dots within a resonant cavity, enabling efficient lateral transfer and accumulation of photocurrent generated from incident electromagnetic radiation, and includes dual modulation doped quantum well structures for dual-wavelength imaging, allowing for separate handling of electron and hole photocurrents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional semiconductor imaging technologies are used, then device structure is simpler, but photocurrent generation and charge accumulation efficiency deteriorates
Solution Approach 1:
The patent employs a composite material structure combining modulation-doped quantum wells with self-assembled quantum dots. The quantum well layer provides a confined potential region for charge carriers, while the quantum dots serve as discrete energy states for efficient photocurrent generation. This composite structure enhances photocurrent generation efficiency by leveraging the complementary properties of both quantum well and quantum dot materials, achieving high productivity without requiring entirely new device architectures.
Solution Approach 2:
The patent implements a nested structure where self-assembled quantum dots are positioned within or adjacent to the modulation-doped quantum well region. The quantum dots (smaller scale) are nested within the broader quantum well structure, creating a hierarchical arrangement that maximizes charge accumulation while maintaining structural integration. This nesting approach allows efficient photocurrent generation within a compact, unified device footprint.
2Quantity of substance
If lateral charge transfer mechanisms are added to improve charge accumulation, then charge storage capability improves, but device complexity increases
Solution Approach 1:
The patent utilizes self-assembled quantum dots that naturally form through spontaneous organization during material growth. These self-assembled structures automatically create the necessary charge transfer pathways and accumulation regions without requiring additional complex transfer mechanisms. The self-assembly process inherently provides the charge storage capability through the quantum dot's discrete energy states and spatial confinement, achieving high charge accumulation capacity while avoiding the complexity of engineered transfer mechanisms.
3Adaptability or versatility
If dual-wavelength imaging capability is implemented, then imaging versatility improves, but device structure complexity increases
Solution Approach 1:
The patent implements local quality variations within the quantum well structure by creating regions with different doping concentrations, well depths, or material compositions. These localized modifications allow different portions of the device to respond to different wavelength ranges. By varying the local properties of the quantum well (such as aluminum composition in AlGaAs barriers or doping profiles), the device achieves dual-wavelength detection capability without requiring entirely separate detector structures, thereby maintaining relatively simple overall device architecture.
Solution Approach 2:
The patent segments the quantum well structure into multiple functional regions, each optimized for detecting specific wavelength ranges. The modulation-doped quantum well is divided into sections with different characteristics (e.g., varying barrier heights, well widths, or doping levels) that correspond to different wavelength sensitivities. This segmentation allows independent optimization of each wavelength channel while maintaining a unified device structure, achieving versatility without proportionally increasing overall complexity.
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 enhances the sensitivity and accuracy of imaging by improving photocurrent generation and charge accumulation, enabling effective single and dual-wavelength imaging by optimizing the transfer and storage of electron and hole charges across the imaging array.
Implementation Method 1
The at least one quantum dot structure of the imaging region generates photocurrent arising from absorption of incident electromagnetic radiation
Implementation Method 2
The at least one modulation doped quantum well structure defines a buried channel for lateral transfer of the photocurrent for charge accumulation in the charge storage region
Implementation Method 3
lateral transfer of the photocurrent for charge accumulation
Implementation Method 4
The at least one quantum dot structure of each imaging cell can be disposed within a resonant cavity that receives the incident electromagnetic radiation
Data Source
AI summary
A semiconductor device that includes an array of imaging cells is provided. Each imaging cell of the array of imaging cells includes an imaging region and first and second charge storage regions. Further, each imaging cell includes first and second quantum dot-in-quantum well (QD-in-QW) structures. The first QD-in-QW structure absorbs an incident electromagnetic radiation having a wavelength within a predetermined first wavelength band and generates a hole photocurrent. The second QD-in-QW structure absorbs an incident electromagnetic radiation having a wavelength within a predetermined second wavelength band and generates an electron photocurrent. Each imaging cell further includes p-type and n-type modulation doped QW structures that defines first and second buried QW channels. The first and second buried QW channels provide for lateral transfer of the hole and electron photocurrents for charge accumulation in the first and second charge storage regions, respectively.