GaN 3D Structure for Red LED Light Output
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Solution Overview
Problem
Current red light emitting diodes using nitride semiconductors face challenges in achieving high light output due to the large ion radius of Eu3+, which causes roughness in crystal growth surfaces, and increasing Eu doping concentration is hindered by high processing costs associated with cutting sapphire substrates into high index planes.
Innovation Solution
A selective growth technique is employed to form a GaN three-dimensional structure with a higher index plane on a conventional base material template, allowing for a Eu-doped GaN layer growth that improves light output without the need for expensive substrate processing, by regulating growth conditions such as temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If Eu doping concentration is increased to improve light output, then emission intensity improves, but crystal growth surface roughness occurs and light output cannot be improved
Solution Approach 1:
The patent changes the crystal orientation parameter from conventional (0001) plane to high index planes such as (10-13) or (01-12) planes. This parameter change allows for higher Eu doping concentrations without causing surface roughness, thereby improving light output while maintaining crystal growth quality.
2Illumination intensity
If sapphire substrate is cut into high index plane to grow Eu-doped GaN layer, then light output improves, but processing cost significantly increases
Solution Approach 1:
The patent uses conventional (0001) plane sapphire substrates that are inexpensive and readily available, replacing the need for expensive custom-cut high index plane substrates. The selective growth technique compensates for the conventional substrate orientation to achieve the desired high light output performance.
Solution Approach 2:
The patent applies preliminary selective growth of GaN layers with specific orientations before growing the Eu-doped GaN layer. This preliminary action creates favorable growth conditions on conventional substrates, enabling high light output without expensive substrate processing.
3Ease of manufacture
If conventional base material template is used, then production cost is low, but Eu doping concentration cannot be increased due to surface roughness
Solution Approach 1:
The patent changes the growth orientation parameter by employing selective growth techniques on conventional substrates, creating high index plane surfaces in situ. This allows increased Eu doping concentration while maintaining low production costs by avoiding expensive substrate processing.
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 method enhances light output of red light emitting semiconductor devices, enabling the integration of red, green, and blue light-emitting diodes for full color displays and high-luminance LED illumination at a lower production cost, while maintaining stable emission wavelengths across ambient temperatures.
Implementation Method 1
a GaN three-dimensional structure having a higher index plane than (0001) plane formed on the lateral face is grown on an undoped GaN layer having (0001) plane
Implementation Method 2
an active layer containing a rare earth element doped so as to replace a metal element of the above-described metal nitride is grown on the lateral face of the above-described three-dimensional structure using an organometallic vapor phase epitaxial method
Data Source
AI summary
A production method of a substrate for nitride semiconductor device comprisinga mask formation step of using a metal nitride as a base material and forming a mask having a prescribed shape on the above-described base material,a three-dimensional structure growth step of growing a three-dimensional structure made of the same material as the base material on the base material having the mask formed thereon using a selective growth technique so that a layer having a higher index plane is formed on the lateral face, andan active layer growth step of growing an active layer containing a rare earth element on the lateral face of the above-described three-dimensional structure using an organometallic vapor phase epitaxial method.