Nanowire Light Emitting Device Overcoming Crystal Defects
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Solution Overview
Problem
Conventional semiconductor light emitting devices suffer from crystal defects due to lattice constant and thermal expansion coefficient differences, leading to poor light emitting properties, especially in nitride semiconductors, and struggle to produce monolithic white light as they require separate phosphor layers and are difficult to miniaturize and precisely arrange nanowires.
Innovation Solution
A nanowire light emitting device with semiconductor nanowires dispersed in an organic binder or transparent conductive polymer, forming a layer with specific conductivity type clad layers, allowing for varied wavelengths and improved light emission efficiency, enabling the production of white light without separate phosphor layers and facilitating miniaturization and precise arrangement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional semiconductor epitaxial layers are used, then the device structure is simple and easy to manufacture, but crystal defects occur due to lattice constant and thermal expansion coefficient differences, deteriorating light emitting properties
Solution Approach 1:
The invention divides the semiconductor layer into multiple quantum well structures with alternating high-bandgap and low-bandgap layers. This segmentation allows each layer to be optimized independently, reducing crystal defects caused by lattice mismatch while maintaining manufacturability through standardized growth processes.
Solution Approach 2:
The invention uses composite material structures combining different semiconductor compounds (e.g., AlGaN and GaN) with different bandgaps in a multi-quantum well configuration. This composite approach enables wavelength control while managing thermal expansion and lattice constant differences through careful material selection and layer design.
2Adaptability or versatility
If the active layer has different compositions to emit light of different wavelengths, then wavelength diversity is achieved, but it becomes difficult to manufacture a monolithic white light emitting device
Solution Approach 1:
The invention segments the active layer into multiple quantum wells with different compositions and thicknesses, where each well emits at a specific wavelength. By stacking these segmented wells, the device achieves broad spectral coverage for white light emission while maintaining a single monolithic structure that is manufacturable through sequential growth.
Solution Approach 2:
The invention applies local quality by varying the composition and thickness of individual quantum well layers at different positions within the active region. Each local region (quantum well) is optimized for a specific wavelength emission, while the overall structure integrates these local variations to produce white light in a monolithic device.
3Length of moving object
If nanowires are directly deposited as PN junction devices, then miniaturization is possible, but individual arrangement in a precise manner becomes difficult
Solution Approach 1:
The invention introduces a patterned substrate or template as an intermediary that guides nanowire growth and positioning. The substrate provides predefined growth sites or chemical gradients that act as mediators, enabling precise spatial arrangement of nanowires during the self-assembly process while maintaining miniaturization benefits.
Solution Approach 2:
The invention performs preliminary patterning of the substrate surface before nanowire deposition, creating predetermined growth sites or chemical markers. This preliminary action establishes the spatial framework that guides subsequent nanowire formation and arrangement, ensuring precise positioning without requiring post-deposition manipulation.
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 nanowire light emitting device achieves higher light emitting efficiency and enables the production of white light by combining semiconductor nanowires with different wavelengths, overcoming crystal defects and miniaturization challenges of conventional devices.
Implementation Method 1
preparing a layer of a mixture composed of a semiconductor nanowire and an organic binder and removing the organic binder therefrom
Data Source
AI summary
The invention provides a nanowire light emitting device and a manufacturing method thereof. In the light emitting device, first and second conductivity type clad layers are formed and an active layer is interposed therebetween. At least one of the first and second conductivity type clad layers and the active layer is a semiconductor nanowire layer obtained by preparing a layer of a mixture composed of a semiconductor nanowire and an organic binder and removing the organic binder therefrom.