Quantum Barrier Indium Gradient for Polarization Reduction
Solution Overview
Problem
Nitride semiconductor light emitting devices face a challenge in minimizing the polarization effect, which separates wave functions of electrons and holes, reducing recombination probability and internal quantum efficiency due to the strong internal field generated in the active layer.
Innovation Solution
The semiconductor light emitting device incorporates a quantum barrier layer with alternating regions of varying indium content, adjusted through slopes, to minimize polarization effects and enhance crystallinity and internal quantum efficiency, with the quantum barrier layer made of AlyInzGa(1-y-z)N and quantum well layer of InxGa(1-x)N, and includes an intermediate region with uniform band gap energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a nitride semiconductor is grown in a polarity direction, then the device can be fabricated with standard processes, but a strong internal field is applied to the active layer due to polarization, separating wave functions of electrons and holes and degrading recombination probability
Solution Approach 1:
The quantum barrier layer is designed with non-uniform indium composition distribution, creating regions with different band gap energies at different locations within the layer. This local variation in material properties allows the structure to maintain effective electron-hole confinement while reducing the net polarization field effect on carrier wave functions.
Solution Approach 2:
The patent employs a composite quantum barrier layer structure combining regions with different indium compositions (AlyInzGa(1-y-z)N with varying y and z values) within a single functional layer. This composite approach enables simultaneous optimization of carrier confinement and polarization field mitigation that cannot be achieved with a uniform composition layer.
2Ease of manufacture
If the quantum barrier layer uses uniform composition, then the structure is simple to fabricate, but it cannot effectively minimize polarization effects or enhance crystallinity
Solution Approach 1:
The quantum barrier layer incorporates spatially varying indium composition with controlled slopes, creating regions of different band gap energies that locally address polarization effects while maintaining overall structural integrity and manufacturability.
Solution Approach 2:
The patent systematically varies the indium composition parameters (y and z values in AlyInzGa(1-y-z)N) across the quantum barrier layer thickness, creating a graded structure that transforms the uniform composition approach into a controlled non-uniform composition design, thereby improving internal quantum efficiency through polarization field management.
3Illumination intensity
If indium content is increased to enhance light emission, then luminescence is improved, but polarization effects are intensified due to the strong internal field
Solution Approach 1:
The quantum barrier layer uses localized regions with different indium compositions to confine carriers effectively (requiring high indium content for strong confinement) while the overall graded structure manages the polarization field, thus achieving high luminescence without excessive polarization effects.
Solution Approach 2:
The composite quantum barrier layer with varying indium compositions enables the structure to simultaneously provide strong carrier confinement (for high luminescence) and reduced net polarization field effect, by combining regions that offer different balances of these two properties.
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
This configuration reduces the polarization effect, enhances crystallinity, and increases internal quantum efficiency, leading to improved luminescence and carrier confinement, while reducing leakage current and driving voltage.
Implementation Method 1
a strong field is applied to the interior of an active layer due to polarization. Thus, wave functions of electrons and holes in the active layer are spatially separated according to the generated internal field
Implementation Method 2
a semiconductor light emitting device is a semiconductor device capable of generating light of various colors according to electron hole recombination in p and n type semiconductor junctions when current is applied thereto
Data Source
AI summary
A semiconductor light emitting device and a fabrication method thereof are provided. The semiconductor light emitting device includes: first and second conductivity-type semiconductor layers; and an active layer disposed between the first and second conductivity-type semiconductor layers and having a structure in which a quantum barrier layer and a quantum well layer are alternately disposed, and the quantum barrier layer includes first and second regions disposed in order of proximity to the first conductivity-type semiconductor layer.