Graphene Avalanche Photodetector for Infrared Quantum Efficiency
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Solution Overview
Problem
Silicon-based CMOS image sensors have lower quantum efficiency for infrared wavelengths compared to visible wavelengths, limiting their effectiveness in applications like biometric sensors and LiDAR systems, and there is a need for compact photodetectors that can detect both infrared and visible light.
Innovation Solution
Avalanche photodetectors are designed with a graphene layer and semiconductor materials like silicon, germanium, or transition metal dichalcogenides, featuring a tunnel barrier layer and electrodes to enhance light detection efficiency across various wavelength bands, utilizing a photo-doping effect to amplify signals with low power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If silicon-based CMOS image sensors are used, then manufacturing compatibility and device integration are improved, but quantum efficiency for infrared wavelengths deteriorates
Solution Approach 1:
The patent employs a composite structure combining silicon-based CMOS technology with graphene layers and tunnel barrier layers. The silicon collector layer maintains manufacturing compatibility while the graphene emitter layer and tunnel barrier layer enhance infrared detection capability, resolving the contradiction between ease of manufacture and infrared quantum efficiency.
2Device complexity
If conventional photodetector structures are used, then device simplicity is maintained, but detection sensitivity and signal amplification deteriorate
Solution Approach 1:
The patent utilizes quantum tunneling effects by precisely controlling the thickness and material properties of the tunnel barrier layer. This parameter change enables significant signal amplification and enhanced detection sensitivity while maintaining a relatively simple layered structure compatible with existing CMOS processes.
3Measurement precision
If larger photodetector structures are used to improve detection performance, then detection sensitivity is improved, but form factor and device size deteriorate
Solution Approach 1:
The patent achieves high detection sensitivity in a compact form factor by using composite materials including graphene with high carrier mobility and tunnel barrier layers with optimized thickness. This composite structure enables effective infrared detection without requiring large device areas, thus maintaining small form factor suitable for portable applications.
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 solution achieves high detection efficiency for both visible and infrared light, reducing noise and enabling compact, low-power devices with improved sensitivity and quick response times, suitable for applications in biometric sensors and LiDAR systems.
Implementation Method 1
utilizing a photo-doping effect to amplify signals with low power consumption
Implementation Method 2
The tunnel barrier layer may include an insulating material, the insulating material having a thickness that is at least a minimum thickness of the insulating material associated with tunneling of electrons and holes in the tunnel barrier layer
Implementation Method 3
avalanche photodetectors configured to utilize a photo-doping effect associated with graphene
Data Source
Figure 1~2
Figure 3A
Figure 3B
AI summary
An avalanche photodetector (10) having a small form factor, effective dark current suppression and a high detection efficiency with respect to both visible light and infrared rays may include a first electrode(11), a collector layer (12) on the first electrode, a tunnel barrier layer (13) on the collector layer, a graphene layer (14) on the tunnel barrier layer, an emitter layer (15) on the graphene layer, and a second electrode (16) on the emitter layer. The photodetector may be included in an image sensor. An image sensor may include a substrate, an insulating layer on the substrate, and a plurality of photodetectors on the insulating layer. The photodetectors may be aligned with each other in a direction extending parallel or perpendicular to a top surface of the insulating layer. The photodetector may be included in a LiDAR system.