Nitride Semiconductor Laser With Electron Barrier Layer

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Solution Overview

Problem

Conventional nitride semiconductor laser elements face challenges in increasing slope efficiency while minimizing power consumption and operating voltage, as thickening the p-side light guide layer to enhance slope efficiency often leads to increased operating voltage and internal optical loss.

Innovation Solution

The nitride semiconductor laser element incorporates an n-side and p-side light guide layer with specific thickness relationships and bandgap energies, along with an electron barrier layer, to prevent electron leakage and absorption, thereby maintaining low operating voltage and enhancing slope efficiency without excessive internal optical loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the thickness of the p-side light guide layer is increased to enhance slope efficiency, then the proportion of guided light distributed in the clad layer decreases, but the operating voltage increases due to increased resistance

Engineering Contradiction:

Improveslope efficiencyVSAvoidoperating voltage

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

An electron barrier layer is introduced as an intermediary between the p-side light guide layer and the p-type clad layer. This layer prevents electron leakage into the light guide layer, maintaining low resistance and operating voltage while allowing the light guide layer to be thickened for improved slope efficiency. The electron barrier layer acts as a mediator that decouples the trade-off between light guiding performance and electrical resistance.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies local quality by creating a region with specifically engineered electron barrier properties at the interface between the p-side light guide layer and p-type clad layer. This localized modification allows the light guide layer to have optimal thickness for light guiding while the interface region provides electron confinement, resolving the contradiction locally without compromising overall device performance.

Inventive Principle:

Principle #3Local quality

2Productivity

If the thickness of the p-side light guide layer is increased to enhance slope efficiency, then light absorption in the clad layer decreases, but internal optical loss increases due to guided light attraction toward the p-type clad layer

Engineering Contradiction:

Improveslope efficiencyVSAvoidinternal optical loss

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The electron barrier layer serves as an optical intermediary that prevents guided light from being attracted toward the p-type clad layer. By positioning this layer between the light guide layer and clad layer, it acts as a barrier to optical field penetration, reducing internal optical loss while allowing the light guide layer to maintain optimal thickness for high slope efficiency.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Use of energy by moving object

If power-to-light conversion efficiency is increased to reduce power consumption, then more energy is converted into laser light, but heat generation increases which reduces long term reliability

Engineering Contradiction:

Improvepower-to-light conversion efficiencyVSAvoidlong term reliability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent converts the potentially harmful effect of high current operation into a benefit by using the high carrier density to fill the light guide layer with electrons, which reduces resistance and operating voltage. This transforms what would normally be a source of heat generation into a mechanism for improving electrical efficiency, thereby enabling high power-to-light conversion while maintaining reliability through reduced thermal load.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 the increase in operating voltage and increases slope efficiency, ensuring efficient power-to-light conversion while minimizing light absorption and internal optical loss, thus improving the energy efficiency and reliability of the nitride semiconductor laser element.

Implementation Method 1

an electron barrier layer which is provided between the p-side light guide layer and the p-type clad layer and is made of a nitride semiconductor having a bandgap energy larger than that of the p-type clad layer

Methodology Applied

Scientific EffectElectron barrier:

Implementation Method 2

The n-side light guide layer is provided between the n-type clad layer and the active layer and is made of a nitride semiconductor having a bandgap energy smaller than that of the n-type clad layer but larger than that of the active layer

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentUS10141720B2Nitride semiconductor laser element

Publication Date: 2018.11.27 PANASONIC HOLDINGS CORP

AI summary

A nitride semiconductor laser element includes an electron barrier layer between a p-side light guide layer and a p-type clad layer. The electron barrier layer has a bandgap energy larger than that of the p-type clad layer. The p-side light guide layer is made of AlxGa1−xN containing no Indium, where 0≤x<1. A film thickness dn of the n-side light guide layer and a film thickness dp of the p-side light guide layer satisfy relationships dp≥0.25 μm and dn≥dp.