GaN LED Growth Temperature Control for Low Voltage
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Solution Overview
Problem
Gallium nitride-based compound semiconductor light-emitting devices with multiple quantum well structures face challenges in achieving low operating voltage and maintaining high light emission output without significant degradation due to aging, especially when well layer thickness is made non-uniform.
Innovation Solution
The method involves controlling the growth temperature differences between well, barrier, and p-type semiconductor layers within specific ranges, and adjusting the growth rate of the barrier layer to ensure excellent crystallinity, low operating voltage, and high light emission intensity, while minimizing the reduction in light emission output over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the thickness of the well layer is reduced to 2 nm or less, then the operating voltage is lowered, but the light emission efficiency deteriorates
Solution Approach 1:
The patent applies local quality by creating a non-uniform thickness distribution within the well layer, where different regions have different thicknesses. This allows the structure to simultaneously achieve low operating voltage (in thinner regions) and high light emission efficiency (in thicker regions), resolving the contradiction between these two parameters.
Solution Approach 2:
The patent changes the thickness parameter of the well layer from a uniform value to a non-uniform distribution. By controlling the thickness to vary within specific ranges (0.5-5 nm in first regions, 1.5-10 nm in second regions), the device achieves both low operating voltage and high light emission efficiency through parameter optimization.
2Power
If the thickness of the well layer is made non-uniform, then the operating voltage is reduced, but the light emission intensity deteriorates due to aging
Solution Approach 1:
The patent uses local quality by dividing the well layer into different regions with different thickness characteristics. The first regions (0.5-5 nm) and second regions (1.5-10 nm) with different area ratios provide localized optimization that maintains low operating voltage while improving aging resistance through the specific thickness distribution pattern.
Solution Approach 2:
The patent creates a composite structure within the well layer by combining regions of different thicknesses. This composite approach, where the well layer comprises multiple regions with distinct thickness characteristics, enables the device to achieve both low operating voltage and enhanced reliability against aging effects.
3Illumination intensity
If the thickness of the well layer is adjusted to 2 to 3 nm, then satisfactory light emission output is attained, but the operating voltage becomes excessively high
Solution Approach 1:
The patent applies local quality by creating regions with different thicknesses within the well layer. The thinner first regions (0.5-5 nm) contribute to low operating voltage, while the thicker second regions (1.5-10 nm) ensure satisfactory light emission output, allowing both requirements to be met simultaneously through spatial differentiation.
Solution Approach 2:
The patent resolves the contradiction by adding a spatial dimension to the thickness parameter. Instead of using a single thickness value, the invention varies the thickness across different spatial regions (first regions and second regions), thereby achieving both low operating voltage and high light emission output through dimensional optimization.
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 approach results in a gallium nitride-based compound semiconductor light-emitting device with reduced operating voltage, enhanced light emission efficiency, and minimal degradation of light emission intensity over time, effectively addressing the limitations of existing devices.
Implementation Method 1
an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer are grown on the aforementioned substrate, in a reactor tube, by use of a Group III organometallic compound and a Group V source gas
Implementation Method 2
the temperature difference (T3−T1) between the growth temperature (T3) of the p-type semiconductor layer and the growth temperature (T1) of the well layer is adjusted to be in a range from 240 to 280° C.
Data Source
AI summary
An object of the present invention is to provide a method for producing a gallium nitride-based compound semiconductor multilayer structure useful for the production of a gallium nitride-based compound semiconductor light-emitting device which can ensure that the operating voltage is reduced, the light emission output is good and the light emission output is less changed due to aging.The inventive production method of a gallium nitride-based compound semiconductor multilayer structure comprises a substrate having thereon an n-type semiconductor layer, a light-emitting layer and a p-type semiconductor layer, the light-emitting layer being disposed between the n-type semiconductor layer and the p-type semiconductor layer, and the light-emitting layer having a multiple quantum well structure formed by alternately stacking a well layer and a barrier layer, wherein at least one well layer has a non-uniform thickness, at least a part of the barrier layer is grown at a higher temperature than the well layer, and the temperature difference between each growth temperature of the well layer, the barrier layer and the p-type semiconductor layer is adjusted to be in a specific range.