Nitride Semiconductor UV Emitter Layer Design
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Solution Overview
Problem
Nitride semiconductor elements that emit ultraviolet light have not yet achieved sufficient enhancement in emission output despite modifications, primarily due to self-absorption and lattice relaxation issues in their structure.
Innovation Solution
A nitride semiconductor element is designed with a multiple quantum well structure comprising a first intermediate layer with a larger band gap energy, a second intermediate layer with a smaller band gap energy, and a light emitting layer, where the first intermediate layer is thinner than the second intermediate layer and light emitting layer, and the barrier layer between the second intermediate layer and the light emitting layer is doped with n-type impurities to enhance recombination and reduce self-absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a multiple quantum well structure is used to improve emission output, then light emission capability is enhanced, but self-absorption occurs due to the band gap energy differences between layers
Solution Approach 1:
The patent applies parameter changes by carefully controlling the band gap energy differences between adjacent well layers. Specifically, the first intermediate layer has a band gap energy that is 0.05-0.20 eV larger than the second intermediate layer, and the second intermediate layer has a band gap energy that is 0.05-0.20 eV larger than the light emitting layer. This controlled parameter differentiation allows photons to pass through intermediate layers without being absorbed, while still maintaining the quantum well structure's light emission enhancement capability.
Solution Approach 2:
The patent implements local quality by assigning different band gap energies to different layers within the quantum well structure. Each layer (first intermediate layer, second intermediate layer, light emitting layer) has a specifically tailored band gap energy suitable for its local function. The intermediate layers have progressively larger band gap energies to prevent self-absorption, while the light emitting layer maintains optimal band gap for ultraviolet emission.
2Reliability
If the thickness of intermediate layers is increased to reduce self-absorption, then light extraction efficiency improves, but device complexity increases
Solution Approach 1:
The patent resolves this contradiction by optimizing the thickness parameters of intermediate layers to be within 1-20 nm. This controlled thickness range is sufficient to prevent self-absorption of ultraviolet light while avoiding excessive complexity in the layer structure. The specific thickness parameters are carefully selected to balance light extraction efficiency with manufacturing feasibility.
3Power
If barrier layers are doped with n-type impurities to enhance recombination, then emission output increases, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies local quality by doping only specific barrier layers with n-type impurities rather than uniformly doping all layers. The barrier layers adjacent to the light emitting layer are selectively doped to enhance carrier recombination and improve emission output, while other layers maintain their original properties. This localized doping approach reduces overall manufacturing complexity compared to uniform doping of the entire structure.
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 effectively suppresses self-absorption and promotes higher emission output by optimizing the band gap energies and thicknesses of the layers, leading to improved light extraction efficiency and increased ultraviolet light emission.
Implementation Method 1
the barrier layer disposed between the second intermediate layer and the light emitting layer is doped with n-type impurities
Implementation Method 2
self-absorption and lattice relaxation issues in their structure
Data Source
AI summary
A nitride semiconductor element includes: an n-side nitride semiconductor layer; an active layer located on the n-side nitride semiconductor layer, the active layer comprising a plurality of well layers formed of a nitride semiconductor and a plurality of barrier layers formed of a nitride semiconductor; and a p-side nitride semiconductor layer located on the active layer. The plurality of well layers includes, in order from the n-side nitride semiconductor layer side: one or more first intermediate layers containing Al, Ga, and N, a second intermediate layer containing Ga and N, and a light emitting layer containing Ga and N and adapted to emit ultraviolet light.