Light Emitting Device Current Spreading Layer
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Solution Overview
Problem
Current light emitting devices face a decrease in optical output due to crystalline defects and damage caused by the dry etching method used to form fine concave-convex structures, which affects long-term operation efficiency.
Innovation Solution
A light emitting device design with a current spreading layer having a higher impurity concentration and convex structures formed by the dry etching method, where the second impurity concentration of the second layer is increased to reduce processing damage and maintain current spreading effects, while the first impurity concentration of the first layer is kept lower to suppress optical absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the dry etching method is used to form fine concave-convex structures, then light extraction efficiency is improved, but crystalline defects and damage occur in the processed region
Solution Approach 1:
The patent changes the impurity concentration parameter of the current spreading layer to reduce processing damage. By optimizing the impurity concentration to a specific range (1×10^18 to 1×10^20 atoms/cm³), the layer becomes more resistant to damage from dry etching while maintaining its current spreading function, thus resolving the contradiction between light extraction efficiency and crystalline defects
Solution Approach 2:
The patent creates a composite structure by forming a current spreading layer with specific impurity concentration between the active layer and the electrode. This composite layer combines the properties of electrical conductivity (for current spreading) and mechanical robustness (resistance to etching damage), thereby achieving both high light extraction efficiency and reduced crystalline defects
2Ease of operation
If a current spreading layer with high impurity concentration is provided, then current spreading effect is improved, but optical absorption increases
Solution Approach 1:
The patent precisely controls the impurity concentration parameter within a specific range (1×10^18 to 1×10^20 atoms/cm³) to balance two opposing requirements: high enough to ensure effective current spreading, but low enough to minimize optical absorption. This parameter optimization resolves the contradiction between current spreading effect and optical absorption
Solution Approach 2:
The patent applies local quality by creating a current spreading layer with specific impurity concentration characteristics in the region between the active layer and electrode. This localized optimization ensures that the current spreading function is enhanced where needed while maintaining low optical absorption in the light extraction path
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 design enhances optical output and reliability during long-term operation by minimizing the impact of processing damage and maintaining current spreading effects, resulting in increased light extraction efficiency and reduced optical absorption.
Implementation Method 1
a light emitting layer (22) capable of emitting emission light
Implementation Method 2
fine concave-convex structures can be formed at the surface of the current spreading layer on the light emitting side. This can improve the light extraction efficiency
Data Source
AI summary
According to one embodiment, a light emitting device includes a light emitting layer, a first electrode, a first and second layers, and a cladding layer. The first layer has a first impurity concentration of a first conductivity type, and allows a carrier to be diffused in the light emitting layer. The second layer has a second impurity concentration of the first conductivity type higher than the first impurity concentration, and includes a first and second surfaces. The first surface is with the first layer. The second surface has a formation region and a non-formation region of the first electrode. The non-formation region includes convex structures with an average pitch not more than a wavelength of the emission light. The cladding layer is provided between the first layer and the light emitting layer and has an impurity concentration of the first conductivity type.