Semiconductor Light-Emitting Element With Variable Well Thickness
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Solution Overview
Problem
Semiconductor light-emitting elements using group III nitride semiconductors often experience decreased light emission efficiency due to unrecombined electrons and holes, especially at higher temperatures and under high current densities, while maintaining the unity of the emitted light wavelength is a challenge.
Innovation Solution
A semiconductor light-emitting element with a multiple quantum well structure comprising at least four well layers and five barrier layers, where the well layers have specific thickness and composition differences to optimize light emission, and the barrier layers are made of GaN with varying thicknesses to enhance light emission efficiency and maintain wavelength unity across temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a multiple quantum well structure with uniform well layers is used, then the light emitting element can be manufactured with standard processes, but the light emission efficiency decreases at high temperatures and high current densities due to unrecombined electrons and holes
Solution Approach 1:
The patent applies local quality by differentiating the well layers into two types: first well layers with a first thickness and second well layers with a second thickness greater than the first thickness. This local differentiation allows specific regions (second well layers) to handle excess carriers more effectively, reducing non-radiative recombination at high temperatures and current densities while maintaining standard manufacturing processes for the overall structure.
Solution Approach 2:
The light emitting layer is segmented into multiple well layers with different thicknesses rather than using uniform well layers. The segmentation into first well layers (thinner) and second well layers (thicker) enables different functional roles: thinner layers for standard light emission and thicker layers for carrier management, thereby improving light emission efficiency under high current density conditions.
2Adaptability or versatility
If the environmental temperature increases, then the device can operate in broader conditions, but the light emission efficiency decreases due to increased non-emitting combination in recombination
Solution Approach 1:
The patent uses local quality by creating second well layers with greater thickness in specific positions within the light emitting layer. These thicker well layers provide enhanced carrier confinement and recombination regions that remain effective at higher temperatures, counteracting the temperature-induced decrease in light emission efficiency while allowing the device to operate across a broader temperature range.
3Power
If high current density is applied to increase output, then the brightness increases, but the light emission efficiency significantly decreases due to excess unrecombined carriers
Solution Approach 1:
The patent segments the well layers into different thickness categories to handle high current density conditions. The second well layers with greater thickness provide additional volume for carrier recombination, reducing the accumulation of unrecombined electrons and holes that would otherwise cause efficiency droop at high current densities, thereby maintaining light emission efficiency while delivering high output brightness.
Solution Approach 2:
The patent changes the thickness parameter of well layers to optimize performance at high current densities. By varying the well layer thickness (creating both thinner first well layers and thicker second well layers), the device can maintain efficient carrier recombination under high injection conditions, preventing efficiency degradation while achieving high power output.
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 effectively suppresses the decrease in light emission efficiency with increasing environmental temperature while maintaining the unity of the emitted light wavelength, improving output even at high current densities.
Implementation Method 1
a light emitting layer that is laminated on the n-type semiconductor layer and composed of a group III nitride semiconductor, the light emitting layer emitting light by passing a current
Data Source
AI summary
While maintaining unity of wavelength of light emitted from a semiconductor light emitting element, decrease of light emission efficiency with an increase in environmental temperature is suppressed. A semiconductor light-emitting element includes: an n-cladding layer; a light emitting layer laminated on the n-cladding layer; and a p-type semiconductor layer laminated on the light emitting layer. The light emitting layer includes a first barrier layer to an eighth barrier layer and a first well layer to a seventh well layer, and a single well layer is sandwiched by two barrier layers. The first well layer to the fifth well layer have a common standard well thickness and a common composition, and the sixth well layer and the seventh well layer are set at a maximum well thickness larger than the common standard well thickness and have a composition whose band gap energy is larger than that of the common composition.