LED Active Layer with Varying Barrier Thicknesses
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Solution Overview
Problem
Conventional light emitting devices face limitations in expanding orientation angle and increasing light power due to issues with current distribution and light extraction efficiency, particularly in white LED packages where light is not uniformly emitted, leading to reduced luminous flux.
Innovation Solution
The light emitting device package incorporates a substrate with a first and second conductive semiconductor layer, an active layer comprising multiple barrier and well layers with varying energy bandgaps and thicknesses, and an electron blocking layer to enhance light emission efficiency and orientation angle by controlling the refractive index and light distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional light emitting devices use standard active layer structure, then device complexity is low, but light extraction efficiency is insufficient and orientation angle cannot be expanded
Solution Approach 1:
The active layer is segmented into multiple quantum wells separated by barrier layers, with each well and barrier having specific thickness ranges (well: 2-10nm, barrier: 3-15nm). This segmentation creates multiple interfaces that enhance light extraction efficiency and expand orientation angle by controlling refractive index distribution throughout the active layer structure.
Solution Approach 2:
Different regions of the active layer are given different local properties through varying well layer thicknesses (2-10nm) and barrier layer thicknesses (3-15nm). The quantum wells have lower refractive index while barrier layers have higher refractive index, creating local quality variations that improve light extraction at different depths and orientations within the active layer.
2Power
If uniform barrier layers are used in active layer, then manufacturing precision is easier to maintain, but light power and luminous flux are limited
Solution Approach 1:
The patent applies parameter changes by specifying optimal thickness ranges for quantum wells (2-10nm) and barrier layers (3-15nm), and controlling composition ratios (x and y values in InxAl1-x-yGay1-yN). These parameter variations optimize light power output while maintaining manufacturability through defined tolerance ranges that balance performance and fabrication capability.
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 increases the orientation angle and light power of the light emitting device package by improving light extraction efficiency, resulting in a substantial increase in luminous flux, as demonstrated by a 5.8% increase in light power compared to traditional methods.
Implementation Method 1
An LED (Light Emitting Device) is a device to convert electrical energy into light energy
Implementation Method 2
at least two of the barrier layers have different energy bandgaps and different thicknesses
Implementation Method 3
issues with current distribution and light extraction efficiency
Data Source
AI summary
Disclosed is a light emitting device and a light emitting device package. The light emitting device includes a substrate; a first conductive semiconductor layer on the substrate; an active layer on the first conductive semiconductor layer; and a second conductive semiconductor layer on the active layer, wherein the active layer includes: a plurality of barrier layers; and a plurality of well layers between the barrier layers, and wherein at least two of the barrier layers have different energy bandgaps and have different thicknesses.