Broadband Optical Device with Interfacial Layer Control
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Solution Overview
Problem
Conventional Si CMOS image sensors have limitations in responsivity, external quantum efficiency, detectivity, and response time, especially when operating in broadband wavelength regions, including visible and infrared light.
Innovation Solution
A broadband multi-purpose optical device is designed with a semiconductor layer, a first active layer having a different light absorption band, a two-dimensional material layer, and interfacial layers to control potential pinning, allowing for a tandem structure with multiple active and 2D material layers to enhance light absorption across a wide spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional Si CMOS image sensor is used, then the device can be manufactured with high process stability and reliability, but the responsivity and external quantum efficiency are insufficient in broadband wavelength regions
Solution Approach 1:
The patent employs a composite structure combining Si CMOS substrate with multiple active layers having different bandgaps (e.g., Ge, InGaAs) and two-dimensional material layers (e.g., graphene, MoS2). This composite architecture enables the device to maintain the manufacturing reliability of Si CMOS while achieving enhanced responsivity across broadband wavelengths by leveraging the complementary optical absorption characteristics of each material layer
Solution Approach 2:
The patent divides the optical detection function into multiple specialized layers, each optimized for specific wavelength ranges. The Si CMOS layer handles visible light, while additional active layers and 2D material layers are segmented to detect specific infrared bands, allowing each segment to operate at optimal performance without compromising the overall device reliability
2Ease of manufacture
If a conventional Si CMOS image sensor is used, then the manufacturing process is simple and cost-effective, but the external quantum efficiency is insufficient in broadband regions
Solution Approach 1:
The patent incorporates preliminary action by pre-optimizing the bandgap composition and thickness of each active layer during the manufacturing process. The multi-layer structure is designed in advance with specific materials (Ge, InGaAs, 2D materials) and configurations that are deposited or grown directly on the Si CMOS substrate, enabling high external quantum efficiency to be built-in during fabrication rather than requiring post-manufacturing adjustments
3Adaptability or versatility
If the wavelength region band is widened to broadband region, then the application range is expanded, but the detectivity and response time of Si based image sensor deteriorate
Solution Approach 1:
The patent applies local quality by assigning different material compositions and optical properties to different layers based on their specific wavelength detection needs. Each active layer and 2D material layer is locally optimized for its target wavelength range, with materials like Ge for mid-infrared and graphene for broad-spectrum detection, thereby maintaining high detectivity across the entire broadband range rather than using a uniform material throughout
4Measurement precision
If multiple active layers and 2D material layers are stacked to enhance broadband absorption, then the light absorption capability is improved, but the device structure becomes more complex
Solution Approach 1:
The patent implements a nested doll structure where multiple active layers and 2D material layers are sequentially stacked and integrated on top of the Si CMOS substrate in a compact configuration. Each layer is nested within the overall device architecture, with interfacial layers and contact structures that seamlessly connect the components, thereby achieving enhanced broadband absorption while managing structural complexity through hierarchical integration
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 device achieves improved optical characteristics, including higher responsivity and external quantum efficiency across visible and infrared regions, enabling effective light detection and absorption in a broad wavelength range.
Implementation Method 1
a semiconductor layer having a light absorption characteristic
Implementation Method 2
a first active layer having a light absorption band different from a light absorption band of the semiconductor layer
Implementation Method 3
a first interfacial layer configured to control a pinning potential of the semiconductor layer and the first active layer
Implementation Method 4
a two-dimensional (2D) material layer adjacent to the first active layer
Data Source
AI summary
A broadband multi-purpose optical device includes a semiconductor layer having a light absorption characteristic, a first active layer having a light absorption band different from a light absorption band of the semiconductor layer, a first two-dimensional (2D) material layer adjacent to the first active layer, and a first interfacial layer configured to control a pinning potential of the semiconductor layer and the first active layer. The broadband multi-purpose optical device may further include at least one second active layer, and may include a tandem structure that further includes at least one second 2D material layer. The first active layer and the second active layer may have different light absorption bands. The broadband multi-purpose optical device may further include a second interfacial layer adjacent to the first 2D material layer.