Time-of-Flight Image Sensors with Quantum Dots for NIR 3D Imaging
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Solution Overview
Problem
Existing image sensors struggle to efficiently capture three-dimensional data in the near-infrared spectrum due to limitations in silicon absorption and the high cost and bulkiness of infrared sensors, while dual wavelength operation for visible light and NIR is needed for improved imaging capabilities.
Innovation Solution
A time-of-flight sensor with a photodetector array using silicon-based light-sensitive diodes containing quantum dot particles that convert NIR light into electrical energy, enabling efficient calculation of time-of-flight for 3D imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dedicated infrared sensors (InGaAs) are used to improve quantum efficiency in the NIR region, then detection performance is improved, but device complexity and manufacturing difficulty increase due to the need for III-V materials and cooling systems
Solution Approach 1:
The patent combines silicon-based photodetectors with quantum dot particles to create a hybrid structure that maintains the advantages of silicon (CMOS compatibility, low cost, small form factor) while adding NIR sensitivity through quantum dots. This merging approach eliminates the need for separate III-V material layers and cooling systems required by traditional InGaAs sensors.
Solution Approach 2:
The invention uses composite materials by integrating quantum dot particles into the silicon photodetector structure. The quantum dots (e.g., PbS, CdSe, or InAs) are deposited on or within the silicon substrate, creating a composite material system that extends the absorption range into the NIR region while maintaining silicon's manufacturing advantages.
2Ease of manufacture
If traditional silicon photodetectors are used to maintain low cost and CMOS compatibility, then manufacturing cost is reduced, but quantum efficiency in the NIR region deteriorates due to sharply decreasing absorption around 900 nm
Solution Approach 1:
The patent changes the optical absorption parameters of silicon by introducing quantum dot particles with specific bandgap energies. These quantum dots absorb NIR photons and transfer carriers to the silicon photodetector, effectively extending the absorption spectrum without changing the underlying silicon material or manufacturing process.
Solution Approach 2:
The quantum dot particles act as intermediaries that bridge the gap between visible and NIR detection. They absorb NIR light that silicon cannot detect and convert it into electrical signals that the silicon photodetector can process, enabling NIR detection while maintaining silicon's cost advantages.
3Measurement precision
If InGaAs based detectors are used to improve quantum efficiency, then detection performance is improved, but device portability and power consumption worsen due to bulkiness and cooling requirements
Solution Approach 1:
The patent replaces expensive, bulky, and cooling-dependent InGaAs detectors with a compact silicon-based solution enhanced by quantum dots. This approach uses readily available silicon technology with added quantum dot functionality, eliminating the need for heavy cooling systems and reducing overall device weight and complexity.
4Measurement precision
If III-V materials are added to silicon processing to improve quantum efficiency, then detection performance is improved, but manufacturing reliability worsens due to contamination risks
Solution Approach 1:
The patent segments the detection function into two parts: the silicon photodetector handles visible light and provides the readout circuitry, while quantum dot particles deposited on or near the silicon surface handle NIR absorption. This segmentation allows each component to be optimized and manufactured separately, then integrated without contamination risks.
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 sensor achieves high efficiency in both visible and NIR spectrums, allowing for low-cost, compact, and low-power 3D imaging with improved detail and penetration through atmospheric conditions.
Implementation Method 1
Each silicon-based, light-sensitive diode includes a photosensitive layer comprising a plurality of quantum dot particles sensitive to a near infrared (NIR) region of an electromagnetic spectrum, wherein the plurality of quantum dot particles converts optical energy into electrical energy to generate an electrical current
Data Source
AI summary
A time-of-flight (ToF) sensor includes a photodetector array and a processing circuit. The photodetector array includes a plurality of photodetectors wherein each photodetector of the photodetector array includes a silicon-based, light-sensitive diode. Each silicon-based, light-sensitive diode includes a photosensitive layer comprising a plurality of quantum dot particles sensitive to a near infrared (NIR) region of an electromagnetic spectrum, wherein the plurality of quantum dot particles converts optical energy into electrical energy to generate an electrical current in response to receiving NIR light having a wavelength in the NIR region. The processing circuit is configured to receive the electrical current and calculate a time-of-flight of the received NIR light based on the electrical current.