Nitride Semiconductor Light Emitting Element With Graded Barrier
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Solution Overview
Problem
Current semiconductor light emitting elements using nitride semiconductors face challenges in enhancing luminous efficiency due to limitations in p-type semiconductor layer configurations and the diffusion of Mg into the light emitting layer, which affects crystallinity and electron blocking efficiency.
Innovation Solution
The semiconductor light emitting element incorporates a p-type semiconductor layer with a specific multi-layer structure, including AlxGa1−xN layers with varying Mg concentrations and thicknesses, and a light emitting layer with a multiple quantum well configuration, where the p-side barrier layer is kept thinner than 3.5 nm to increase hole injection efficiency and maintain high crystallinity, while the Al composition ratio is gradually increased towards the p-type semiconductor layer to enhance electron blocking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the p-side barrier layer is made thicker to improve electron blocking, then electron blocking efficiency is improved, but hole injection efficiency deteriorates and luminous efficiency decreases
Solution Approach 1:
The p-side barrier layer is segmented into a first barrier layer and a second barrier layer with different thicknesses and Al compositions. The first barrier layer (thinner, lower Al) is positioned adjacent to the light emitting layer to maintain hole injection, while the second barrier layer (thicker, higher Al) is positioned away from the light emitting layer to enhance electron blocking, thus resolving the contradiction between electron blocking efficiency and hole injection efficiency.
2Productivity
If Mg concentration is increased in the p-type semiconductor layer to improve hole injection, then hole injection efficiency is improved, but Mg diffusion into the light emitting layer increases causing crystallinity deterioration
Solution Approach 1:
The first barrier layer acts as an intermediary layer between the light emitting layer and the high-Mg concentration second barrier layer. This intermediary structure prevents direct contact between high Mg concentration regions and the light emitting layer, thereby suppressing Mg diffusion while still enabling effective hole injection through the graded Al composition structure.
3Reliability
If Al composition ratio is increased towards the p-type semiconductor layer to improve electron blocking, then electron blocking efficiency is improved, but manufacturing complexity increases due to precise composition control requirements
Solution Approach 1:
Different Al composition ratios are assigned to different regions of the p-side barrier layer. The first barrier layer has a lower Al composition (0.05-0.20) suitable for regions requiring high hole injection, while the second barrier layer has a higher Al composition (0.20-0.40) suitable for regions requiring strong electron blocking. This local quality differentiation optimizes performance while providing clear manufacturing guidance for composition control.
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 significantly increases luminous efficiency by improving hole injection and electron blocking, while suppressing Mg diffusion and maintaining high crystallinity, leading to enhanced light emission performance across a wide current range.
Implementation Method 1
a light emitting layer with a multiple quantum well configuration
Implementation Method 2
the Al composition ratio is gradually increased towards the p-type semiconductor layer to enhance electron blocking
Implementation Method 3
the p-side barrier layer is kept thinner than 3.5 nm to increase hole injection efficiency
Implementation Method 4
Semiconductor light emitting elements such as light emitting diodes, laser diodes, etc., that use nitride semiconductors
Implementation Method 5
suppressing Mg diffusion and maintaining high crystallinity
Data Source
AI summary
According to one embodiment, a semiconductor light emitting element includes an n-type semiconductor layer including a nitride semiconductor, a p-type semiconductor layer and a light emitting layer. The p-type semiconductor layer includes a first p-side layer of Alx1Ga1−x1N (0≦̸x1<1) including Mg, a second p-side layer of Alx2Ga1−x2N (0<x2<1) including Mg and a third p-side layer of Alx3Ga1−x3N (x2<x3<1) including Mg. The light emitting layer is provided between the n-type semiconductor layer and the second p-side layer. The light emitting layer includes barrier layers and well layers. Each of the well layers is provided between the barrier layers. A p-side barrier layer of the barrier layers most proximal to the second p-side layer includes a first layer of Alz1Ga1−z1N (0≦̸z1), and a second layer of Alz2Ga1−z2N (z1<z2<x2).