Light-Emitting Device With Roughened Surface And Composition Gradient
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Solution Overview
Problem
Conventional light-emitting diodes (LEDs) face challenges in enhancing light extraction efficiency and reliability due to limitations in surface roughening techniques, which affect the scattering and emission of light from semiconductor layers.
Innovation Solution
A light-emitting device with a semiconductor structure featuring a roughened surface and an unroughened upper surface, where the roughened surface is exposed and covered by an electrode, and the atomic percentage of Group III elements gradually decreases from the electrode to the light-emitting stack, improving light scattering and emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the semiconductor layer surface is roughened to enhance light scattering, then light extraction efficiency is improved, but manufacturing precision and surface uniformity deteriorate
Solution Approach 1:
The patent applies local quality by creating a dual-surface structure where only specific regions of the semiconductor layer are roughened. The first surface (exposed region) is roughened to scatter light, while the second surface (covered region) remains smooth for reliable electrode contact. This selective roughening resolves the contradiction by localizing the light-scattering function to specific areas rather than treating the entire surface uniformly.
2Illumination intensity
If the entire semiconductor layer surface is roughened, then light scattering is maximized, but electrode contact reliability and electrical performance deteriorate
Solution Approach 1:
The patent divides the semiconductor layer surface into two distinct regions with different surface qualities: an exposed region with roughened surface for optimal light scattering, and a covered region with smooth surface for reliable electrode contact. This spatial differentiation allows each region to optimize its specific function without compromising the other.
Solution Approach 2:
The semiconductor layer surface is segmented into functionally distinct zones: the first surface region that interfaces with the electrode (smooth) and the second surface region that is exposed for light emission (roughened). This segmentation enables simultaneous optimization of electrical contact and optical performance.
3Reliability
If conventional surface roughening techniques are used, then light extraction is enhanced, but process stability and manufacturing reliability deteriorate
Solution Approach 1:
The patent employs selective roughening techniques that are applied in advance to specific regions before electrode deposition. By pre-defining which areas require roughening and which require smoothness, the manufacturing process achieves better control and stability. The selective approach allows for more predictable outcomes compared to global roughening, improving process repeatability.
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 described structure enhances light extraction efficiency and reliability by effectively scattering light from the active layer, leading to improved electrical performance and process stability during manufacturing.
Implementation Method 1
The first portion has a roughed surface... effectively scattering light from the active layer
Data Source
AI summary
A light-emitting device is provided. The light-emitting device comprises The light-emitting device comprises a light-emitting stack comprising a first semiconductor layer, a second semiconductor layer and an active layer between the first semiconductor layer and the second semiconductor layer; and a third semiconductor layer on the light-emitting stack and comprising a first sub-layer, a second sub-layer and a roughened surface, wherein the first sub-layer has the same composition as that of the second sub-layer, and the second sub-layer is farther from the light-emitting stack than the first sub-layer; wherein the first sub-layer and the second sub-layer each comprises a Group III element and a Group V element, and an atomic ratio of the Group III element to the Group V element of the first sub-layer is less than an atomic ratio of the Group III element to the Group V element of the second sub-layer.