JFET Image Sensor With Quantum Dots for Low Dark Noise
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Solution Overview
Problem
The reduction in pixel size of high-resolution image sensors leads to decreased light-receiving areas, resulting in increased dark noise and reduced signal-to-noise ratios, making it difficult to obtain clear images.
Innovation Solution
The development of opto-electronic devices with a junction field-effect transistor (JFET) structure, incorporating quantum dots and a transparent matrix layer, which amplifies photocurrent and reduces dark noise by efficiently transferring charge carriers, thereby improving the signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixel size is reduced to increase resolution, then image sensor resolution is improved, but light-receiving area decreases and dark noise increases
Solution Approach 1:
The patent introduces a specialized transistor structure with quantum dots as an intermediary component between the light-receiving element and the signal processing circuit. The quantum dots act as a mediator that amplifies the weak photocurrent signal from small pixels while suppressing dark noise, enabling high resolution without sacrificing light-receiving area.
Solution Approach 2:
The patent changes the electrical parameters of the transistor by using quantum dots with specific size ranges (2-10 nm) and controlling doping concentrations (first doping concentration of 1×10^19 to 1×10^21 atoms/cm³ for source/drain, 1×10^17 to 1×10^19 atoms/cm³ for channel). These parameter changes enable the transistor to operate with high gain and low noise, resolving the contradiction between small pixel size and high signal quality.
2Measurement precision
If pixel size is reduced, then resolution increases, but signal-to-noise ratio decreases
Solution Approach 1:
The quantum dot-based transistor serves as an intermediary signal conditioning stage that improves signal-to-noise ratio before further processing. The quantum dots provide photomultiplication effect that amplifies the signal while the junction field-effect transistor structure filters out noise, maintaining high reliability even with reduced pixel size.
Solution Approach 2:
The patent employs a composite structure combining quantum dots with semiconductor materials (such as Si, Ge, or III-V族 compounds) to create a hybrid transistor device. This composite material approach leverages the quantum confinement effect of quantum dots for signal amplification and the electrical properties of semiconductor materials for noise suppression, achieving high signal-to-noise ratio in small pixels.
3Productivity
If quantum dots are embedded in transparent matrix layer, then charge carrier transfer efficiency is improved, but device complexity increases
Solution Approach 1:
The patent uses a thin transparent matrix layer (such as SiO2, Si3N4, or TiO2 with thickness of 1-10 nm) to embed quantum dots. This thin film approach provides sufficient encapsulation and charge carrier transfer pathways while minimizing the added structural complexity and maintaining device compactness.
Solution Approach 2:
The patent applies the transparent matrix layer selectively only in regions where quantum dots are positioned, rather than covering the entire device surface. This localized application reduces unnecessary material usage and structural complexity while maintaining high charge carrier transfer efficiency at the quantum dot-matrix interface where it is most needed.
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 opto-electronic devices achieve low dark noise and high signal-to-noise ratios, enabling clear image capture even with weak incident light and allowing for further reduction in pixel size to increase image sensor resolution.
Implementation Method 1
a plurality of quantum dots 104 arranged on a transparent matrix layer 103... When light is incident on the quantum dots 104, the quantum dots 104 absorbs the light and generate photocarriers
Implementation Method 2
the transparent matrix layer 103 efficiently transferring charge carriers... which amplifies photocurrent and reduces dark noise by efficiently transferring charge carriers
Implementation Method 3
opto-electronic devices having a junction field-effect transistor (JFET) structure... which amplifies photocurrent
Data Source
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AI summary
Provided is an opto-electronic device (100) having low dark noise and a high signal-to-noise ratio. The opto-electronic device may include: a first semiconductor layer (101) doped to have a first conductivity type; a second semiconductor layer (102) disposed on an upper surface of the first semiconductor layer and doped to have a second conductivity type electrically opposite to the first conductivity type; a transparent matrix layer (103) disposed on an upper surface of the second semiconductor layer; a plurality of quantum dots (104) arranged to be in contact with the transparent matrix layer; and a first electrode (105) provided on a first side of the transparent matrix layer and a second electrode (106) provided on a second side of the transparent matrix layer opposite to the first side, wherein the first electrode and the second electrode are electrically connected to the second semiconductor layer.