DBR Mask Window Structure for Low-Dislocation GaN Light Emission
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Solution Overview
Problem
High dislocation density in GaN-based materials poses challenges for the growth of high-quality crystalline materials on heterogeneous substrates, such as sapphire, which is detrimental for GaN-based optoelectronic devices used in photoelectric applications.
Innovation Solution
A light emitting device is designed with a DBR mask layer having a window that exposes the substrate, where the first semiconductor layer is either located within or on the side of the window, and the active and second semiconductor layers are stacked sequentially, reducing dislocation density and improving light extraction efficiency through the arrangement of the DBR mask layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If GaN-based materials are grown on heterogeneous substrates like sapphire, then the device can be manufactured, but high dislocation density occurs
Solution Approach 1:
The patent segments the growth process by introducing a patterned mask layer with windows that divides the substrate surface into multiple regions. This allows selective epitaxial growth in specific areas, enabling control over dislocation propagation paths and reducing overall dislocation density while maintaining manufacturability on heterogeneous substrates.
Solution Approach 2:
The patent applies local quality by creating regions with different properties through the patterned mask structure. Areas under the windows have different growth characteristics compared to areas under the mask, allowing optimization of crystal quality in specific regions while maintaining overall device manufacturability.
2Manufacturing precision
If a window configuration is used in the DBR mask layer, then dislocation density is reduced, but device structure becomes more complex
Solution Approach 1:
The DBR mask layer serves multiple functions simultaneously: it acts as a reflective distributed Bragg reflector for light extraction and as a patterned mask for controlling epitaxial growth. This multi-functionality reduces the need for separate mask structures, thereby reducing overall device complexity while achieving dislocation density reduction through the window configuration.
Solution Approach 2:
The patent merges the DBR structure and the mask layer into a single integrated component. The DBR mask layer combines the optical reflection function of the DBR with the pattern formation function of the mask, eliminating the need for separate structures and simplifying the overall device architecture while maintaining the dislocation reduction benefit.
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 effectively reduces dislocation density during epitaxial growth and enhances light extraction efficiency of the light emitting device, addressing the limitations of existing technologies in achieving low dislocation density and improved performance in GaN-based optoelectronic devices.
Implementation Method 1
a distributed bragg reflector (DBR) mask layer on a side of the substrate... enhances light extraction efficiency by improving reflectivity
Implementation Method 2
a light emitting unit includes a first semiconductor layer, an active layer and a second semiconductor layer which are stacked sequentially
Data Source
AI summary
A light emitting device includes: a substrate; a DBR mask layer on a side of the substrate, the DBR mask layer being provided with a window exposing the substrate, the window including an opening end away from the substrate and a bottom wall end close to the substrate, and on a plane where the substrate is located, an orthographic projection of the opening end falling within an orthographic projection of the bottom wall end; and a light emitting unit. The light emitting unit includes an active layer located on a side, away from the substrate, of the DBR mask layer. Providing the window on the DBR mask layer may reduce dislocation density during epitaxial growth of the light emitting unit, and arrangement of the DBR mask layer may improve light extraction efficiency of the light emitting device.