Chip-Scale LED Dual Reflector Structure for Uniform N-Via Luminance
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Solution Overview
Problem
Conventional chip-scale package LEDs suffer from reduced luminance due to light absorption in non-emitting areas, particularly in the n-vias, resulting in dimmed or darkened regions within the light-emitting area.
Innovation Solution
Incorporation of a second composite reflector structure comprising a transparent conductive oxide (TCO) layer, dielectric layer, multilayer reflector (MLR) layer, and metal layer within the n-vias to redirect light away from absorption by the metal layer, enhancing overall luminance and reducing darkened regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal layer is used for electrical contact in n-vias, then electrical conductivity is improved, but light absorption increases causing darkened regions
Solution Approach 1:
The patent applies composite materials by combining multiple layers (transparent conductive oxide layer, dielectric layer, multilayer reflector layer, and metal layer) within the n-vias. This composite structure allows the metal layer to provide electrical conductivity while the transparent conductive oxide and multilayer reflector layers redirect light away from the metal, preventing light absorption and darkened regions.
2Illumination intensity
If light is reflected towards the output surface, then luminance is improved, but structural complexity increases
Solution Approach 1:
The patent segments the reflector function into multiple distinct layers within the n-vias: a transparent conductive oxide layer for electrical contact and light transmission, a dielectric layer for insulation and optical management, and a multilayer reflector layer for light redirection. This segmentation allows each layer to perform its specific function efficiently while collectively achieving high luminance.
Solution Approach 2:
The patent implements a nested structure where the transparent conductive oxide layer, dielectric layer, and multilayer reflector layer are arranged concentrically within the n-vias. This nesting allows multiple functions (electrical contact, insulation, light reflection) to be integrated in a compact vertical arrangement, improving luminance without proportionally increasing horizontal device complexity.
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 second composite reflector increases overall luminance by reflecting light towards the output surface, minimizing absorption losses and eliminating darkened regions, thereby improving the LED's brightness and uniformity.
Implementation Method 1
The second composite layer is structured to act as an electrical contact to the second doped layer and as an optical reflector
Implementation Method 2
a multilayer reflector (MLR) layer directly on the dielectric layer
Implementation Method 3
Radiative recombination at the active region 13 of charge carriers of an LED drive current result in light being emitted by the active region 13
Data Source
AI summary
An LED includes a first composite layer on a first of its doped layers. Primary vias extend through the first composite layer, through the first doped layer and active region of the LED, and into a second doped layer thereof. A second composite layer (TCO, dielectric, multilayer reflector, and metal layers) is positioned on the second doped layer within the primary vias, on lateral surfaces of the primary vias, and on portions of the first composite layer. A dielectric spacer layer separates the first composite layer, the first doped layer, and the active region from the second composite layer. The TCO layer includes embedded electrical contact areas outside the primary vias, each being separated from the first doped layer by the first composite layer and the dielectric spacer layer. The second composite layer within the primary vias increases LED luminance (by reducing absorption, increasing reflectivity, and reducing darkening or dimming).