Non-Polar Light Emitting Device Package for Color Stability
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Solution Overview
Problem
Conventional light emitting devices grown in a polar direction suffer from reduced recombination efficiency due to built-in electric fields, leading to unstable color reproduction and red-shift of wavelengths, affecting their color stability and performance.
Innovation Solution
A light emitting device package with a light emitting structure grown in a non-polar direction on a substrate, featuring a buffer layer with controlled dislocation density, a reflective layer with a double-layered superlattice structure, and a light-transmissive resin layer with phosphors for enhanced color purity and heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If light emitting device is grown in polar direction, then light emission function is achieved, but recombination efficiency is reduced and color stability deteriorates
Solution Approach 1:
The patent changes the crystal growth direction parameter from polar (c-axis) to non-polar (a-plane or m-plane), which fundamentally alters the polarization characteristics and eliminates the built-in electric field that causes carrier separation and reduces recombination efficiency
Solution Approach 2:
The patent employs composite material structures including buffer layers with specific dislocation densities (1×10^9/cm² to 1×10^10/cm²) and multi-layer semiconductor structures (AlGaN/GaN superlattices) to manage dislocations and enhance optical properties while maintaining stable color reproduction
2Temperature
If conventional light emitting device structure is used, then manufacturing simplicity is maintained, but heat dissipation performance is insufficient
Solution Approach 1:
The patent introduces a metal layer as a thermal intermediary component between the light emitting device and the package body, creating an efficient heat transfer pathway that mediates thermal management without requiring fundamental changes to the device structure
Solution Approach 2:
The patent segments the heat dissipation function into distinct components: the light emitting device generates heat, the metal layer conducts and distributes heat, and the package body dissipates heat to the environment, allowing each component to be optimized independently
3Reliability
If light emitting device is sealed with light-transmissive resin layer, then device protection is achieved, but color purity may be compromised
Solution Approach 1:
The patent applies local quality by incorporating phosphors specifically within the light-transmissive resin layer at targeted locations, allowing the resin to simultaneously provide protection and enhance color purity through localized phosphor conversion of the emitted light
Solution Approach 2:
The patent utilizes phosphor materials that absorb specific wavelengths and emit converted wavelengths, actively changing the color characteristics of the light to achieve higher color purity (at least 0.5) while maintaining device protection
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 solution achieves stable color reproduction, improved heat dissipation, and increased doping efficiency, resulting in a light emitting device package with enhanced electrical and optical characteristics.
Implementation Method 1
Light emitting diodes are a kind of semiconductor device that converts electricity into light (e.g., infrared light) by using the characteristics of a compound semiconductor
Implementation Method 2
The light-transmissive resin layer may include at least one of a plurality of phosphors
Implementation Method 3
a metal layer disposed on a rear surface of the body to face the light emitting device
Implementation Method 4
The buffer layer may have a dislocation density of 1×10E9/cm2 to 1×10E10/cm2
Data Source
AI summary
A light emitting device package includes a body having a cavity, at least one insulating layer disposed on the body, first and second electrode layers disposed on the insulating layer and electrically isolated from each other, at least one light emitting device disposed on a bottom surface of the cavity and electrically connected to the first and second electrode layer, a light-transmissive resin layer sealing the light emitting device disposed in the cavity, and a metal layer disposed on a rear surface of the body to face the light emitting device, wherein the light emitting device is grown in an m-direction on the (1123) plane of a substrate and includes a light emitting structure including a first conductive semiconductor layer, and active layer, and a second conductive semiconductor layer.