Nanorod LED Core-Shell Structure for Defect Reduction
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Solution Overview
Problem
Nitride-based semiconductor crystals used in blue and ultraviolet LEDs suffer from defects due to lattice constant mismatches and thermal expansion coefficient differences, leading to reduced luminous efficiency as electrical charge injection results in heat energy rather than light energy.
Innovation Solution
A nanorod light emitting device structure is developed, featuring a nitride semiconductor layer with a mask layer having through holes, light emitting nanorods with a nanocore and emission layer, and conductive layers to enhance current injection efficiency and minimize crystal defects, including a core-shell nanorod structure to reduce dislocation and increase light emission surface area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nitride-based compound semiconductor crystals are used to produce blue and ultraviolet LEDs, then the LEDs can produce superior physical and chemical characteristics and extended application range, but the LEDs suffer from multiple defects due to lattice constant mismatch and thermal expansion coefficient difference, resulting in reduced luminous efficiency
Solution Approach 1:
The invention segments the semiconductor structure into nanorod units with core-shell configuration. The nanorods are formed by patterning the nitride semiconductor layer into discrete cylindrical structures, where each nanorod acts as an independent light-emitting unit. This segmentation reduces the overall defect impact by isolating dislocations to specific regions and prevents defect propagation across the entire device area.
Solution Approach 2:
The invention implements a core-shell nested structure where a first nitride semiconductor layer forms the core and a second nitride semiconductor layer forms the shell. The core nanorod is completely enclosed by the shell layer, creating a nested configuration. This nested structure allows the inner core to provide stable crystal growth while the outer shell reduces dislocation density and improves overall crystal quality, thereby enhancing luminous efficiency.
2Ease of manufacture
If conventional LED structures are used, then the manufacturing process is simpler, but the current injection efficiency is lower due to crystal defects
Solution Approach 1:
The invention performs preliminary defect management by forming the core-shell nanorod structure before final device assembly. The mask layer is deposited and patterned in advance to define the nanorod positions and dimensions. Through holes are created through the mask layer prior to nanorod formation, allowing precise control of nanorod growth locations. This preliminary structuring enables subsequent epitaxial growth to proceed with reduced defect formation, improving current injection efficiency without complicating the overall manufacturing flow.
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 nanorod light emitting device improves current injection efficiency and luminous efficiency by reducing crystal defects and increasing the light emission surface area, thereby enhancing the overall performance of LEDs.
Implementation Method 1
When electrons and holes are combined in an active layer of a semiconductor light emitting device, energy corresponding to an energy bandgap of the active layer may be emitted in the form of light, a phenomenon known as electroluminescence.
Data Source
AI summary
A nanorod light emitting device and a method of manufacturing the same. The nanorod light emitting device may include at least one nitride semiconductor layer, light emitting nanorods formed on the nitride semiconductor layer and spaced apart from each other, and a first filling layer, a conductive layer, and a second filling layer formed in spaces between the light emitting nanorods.