GaN Quantum Well Light-Emitting Element With Varying Orthogonal Thickness
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Solution Overview
Problem
Nitride semiconductor light-emitting elements with a GaN-based semiconductor light-emitting layer face low external quantum efficiency, unlike those with an AlGaN-based semiconductor, where segregation of Ga cannot occur, hindering improvement in light emission efficiency.
Innovation Solution
A nitride semiconductor light-emitting element with a quantum well structure having a GaN-based semiconductor well layer and varying thickness in the orthogonal plane, combined with an off-angle sapphire substrate for epitaxial growth, enabling efficient light emission and improved external quantum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a GaN-based semiconductor light-emitting layer is used, then the device structure is simpler, but the external quantum efficiency becomes low because Ga segregation cannot occur
Solution Approach 1:
The patent introduces Al composition variation at specific locations within the light-emitting layer. The Al composition is locally increased in certain regions to create Ga segregation effects, while other regions maintain different Al compositions. This local compositional differentiation enables efficient light emission in specific areas without requiring complete AlGaN structure throughout the device.
Solution Approach 2:
The light-emitting layer is constructed as a composite structure combining GaN-based semiconductor with regions of varying Al composition. This composite approach integrates the structural simplicity of GaN-based materials with the efficient light emission properties of AlGaN-like regions, achieving both structural advantage and high external quantum efficiency.
2Loss of energy
If AlGaN-based semiconductor is used to improve external quantum efficiency through Ga segregation, then the light emission efficiency improves, but the device cannot be applied to wavelengths where Ga segregation is ineffective
Solution Approach 1:
The patent systematically varies the Al composition parameter throughout the light-emitting layer to achieve different optical properties in different regions. By controlling Al composition gradients and local Al-rich regions, the device can be tuned for efficient light emission across multiple wavelength ranges, including regions where traditional Ga segregation mechanisms are ineffective.
3Device complexity
If the light-emitting layer is composed of pure GaN-based semiconductor, then the material system is simpler, but the emission intensity is insufficient for practical applications
Solution Approach 1:
The patent creates local Al-rich regions within the GaN-based light-emitting layer to enhance emission intensity in specific areas. These localized compositional modifications provide high emission intensity spots that drive overall device performance, while the majority of the structure maintains the simpler GaN-based composition.
Solution Approach 2:
The light-emitting layer combines GaN-based semiconductor material with Al-containing regions to create a composite structure. This composite material system leverages the high emission intensity characteristics of AlGaN-like regions while maintaining the structural advantages of GaN-based materials, achieving sufficient overall emission intensity for practical 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 enhances the external quantum efficiency by creating a portion capable of efficient light emission in the orthogonal plane, improving the emission intensity and peak emission wavelength, resulting in a composite peak emission spectrum with increased integrity.
Implementation Method 1
a nitride semiconductor light-emitting element with a light-emitting layer composed of an InGaN-based semiconductor, in which light emission is occurred by recombination of the carrier (electrons and holes)
Implementation Method 2
at least each layer from the main surface of the sapphire substrate to the surface of the active layer is an epitaxially grown layer
Data Source
AI summary
The nitride semiconductor light-emitting element comprises a light-emitting element structure portion having a plurality of nitride semiconductor layers including at least an n-type layer, an active layer and a p-type layer. The active layer has a quantum well structure comprising at least one well layer composed of a GaN-based semiconductor. In the well layer, the shortest distance between a first surface on the n-type layer side and a second surface on the p-type layer side varies in an orthogonal plane to the layering direction of the nitride semiconductor layers, and the peak emission wavelength of light emitted from the light-emitting element structure portion is shorter than 354 nm.