Nitride Light Emitter with Transparent Contact for Mode Confinement
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Solution Overview
Problem
The existing configuration of blue-violet laser diodes in lithography equipment faces issues with heat generation and reduced slope efficiency due to the vertical transverse mode shifting towards the p-type GaN contact layer and increased optical loss when the p-type AlGaN cladding layer is either thin or thick.
Innovation Solution
A nitride semiconductor light-emitting device is designed with a transparent conductive layer that confines the vertical transverse mode, eliminating the need for a p-type contact layer and reducing resistance, while a current constriction layer efficiently injects current into the active area, thereby reducing heat generation and improving slope efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the p-type AlGaN cladding layer is thickened to prevent light propagation mode shifting, then the vertical transverse mode confinement is improved, but the resistance and optical loss are increased resulting in higher heat generation and reduced slope efficiency
Solution Approach 1:
A transparent conductive layer is introduced as an intermediary between the p-type AlGaN cladding layer and the p-type contact layer. This transparent conductive layer has high transparency to laser light and high electrical conductivity, serving as a mediator that allows light to pass through while providing low-resistance electrical contact, thus resolving the conflict between optical confinement and electrical performance
Solution Approach 2:
The invention changes the electrical conductivity parameter of the cladding layer region by introducing a transparent conductive layer with high conductivity. This parameter change allows the system to achieve both good optical confinement (through the AlGaN layer) and low electrical resistance (through the transparent conductive layer), resolving the trade-off between optical loss and heat generation
2Reliability
If a p-type GaN contact layer is provided to contact the p-side electrode, then the electrical contact is improved, but the vertical transverse mode shifts toward the contact layer resulting in decreased amplification efficiency
Solution Approach 1:
The transparent conductive layer serves as an intermediary that separates the electrical contact function from the optical waveguide function. It provides the necessary electrical contact to the p-side electrode while maintaining optical transparency, preventing the vertical transverse mode from shifting toward the contact layer and preserving amplification efficiency
Solution Approach 2:
The invention segments the contact structure into multiple functional layers: the p-type AlGaN cladding layer for optical confinement, the transparent conductive layer for electrical contact with optical transparency, and the p-type contact layer for electrode attachment. This segmentation allows each layer to optimize its specific function without interfering with others
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 reduces heat generation and enhances slope efficiency by confining the vertical transverse mode with a transparent conductive layer and efficiently injecting current through a current constriction layer, minimizing optical loss during light propagation.
Implementation Method 1
a transparent conductive layer located on the second conductivity-type nitride semiconductor layer and transparent to light generated from the active layer
Implementation Method 2
a current constriction layer located in a part of the second conductivity-type nitride semiconductor layer
Implementation Method 3
light generated from the active layer
Data Source
AI summary
A nitride semiconductor light-emitting device includes: a first conductivity-type nitride semiconductor layer, an active layer located over the first conductivity-type nitride semiconductor layer, a second conductivity-type nitride semiconductor layer located over the active layer, a current constriction layer located in a part of the second conductivity-type nitride semiconductor layer, and a transparent conductive layer located on the second conductivity-type nitride semiconductor layer and transparent to light generated from the active layer.