Nitride Semiconductor Laser Diode with Graded Bandgap Clad Layer

Solution Overview

Problem

Current nitride semiconductor laser diodes face challenges in reliability and mass productivity due to technical limitations, particularly with the need for a dedicated electron barrier layer that complicates the thin film growth and can lead to dopant diffusion and reduced optical confinement.

Innovation Solution

A semiconductor laser diode structure where the p-type clad layer functions as both the electron barrier and optical guide layer, with a band gap that decreases as it moves away from the active layer, allowing for the omission of a dedicated electron barrier layer and using a nitride semiconductor layer with Al that gradually decreases in concentration, facilitating efficient recombination and growth.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a dedicated electron barrier layer is used, then electron blocking capability is improved, but device complexity and manufacturing difficulty increase

Engineering Contradiction:

Improveelectron blocking capabilityVSAvoidlayer structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the electron barrier layer and clad layer into a single integrated structure. The clad layer is designed with specific band gap characteristics (greater than the active layer but less than the electron barrier layer) that enable it to perform both optical confinement and electron blocking functions simultaneously, eliminating the need for a separate dedicated electron barrier layer.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The clad layer is designed to serve multiple functions: it acts as an optical guide for light confinement and simultaneously functions as an electron barrier. By carefully controlling the band gap energy profile (decreasing as distance from the active layer increases), the single clad layer structure achieves both electron blocking and optical guidance without requiring additional dedicated layers.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If a dedicated electron barrier layer is used, then electron blocking is improved, but manufacturing precision and productivity decrease

Engineering Contradiction:

Improveelectron blocking capabilityVSAvoidmass productivity

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent combines the electron barrier layer and clad layer into a single integrated structure. The clad layer is designed with specific band gap characteristics (greater than the active layer but less than the electron barrier layer) that enable it to perform both optical confinement and electron blocking functions simultaneously, eliminating the need for a separate dedicated electron barrier layer.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent employs gradual parameter changes in the band gap energy profile of the clad layer, which decreases as distance from the active layer increases. This continuous parameter variation optimizes both electron blocking and optical confinement while simplifying the manufacturing process by eliminating discrete layer interfaces that would require precise alignment and multiple growth steps.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If a dedicated electron barrier layer is used, then electron blocking is improved, but dopant diffusion increases

Engineering Contradiction:

Improveelectron blocking capabilityVSAvoiddopant diffusion

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent combines the electron barrier layer and clad layer into a single integrated structure. The clad layer is designed with specific band gap characteristics (greater than the active layer but less than the electron barrier layer) that enable it to perform both optical confinement and electron blocking functions simultaneously, eliminating the need for a separate dedicated electron barrier layer.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent employs gradual parameter changes in the band gap energy profile of the clad layer, which decreases as distance from the active layer increases. This continuous parameter variation optimizes both electron blocking and optical confinement while simplifying the manufacturing process by eliminating discrete layer interfaces that would require precise alignment and multiple growth steps.

Inventive Principle:

Principle #35Parameter changes

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 enhances light emitting efficiency, simplifies the laser structure, prevents dopant diffusion, and improves reliability and mass productivity by eliminating the need for a dedicated electron barrier layer, thereby addressing the limitations of existing nitride semiconductor laser diodes.

Implementation Method 1

a clad layer on the semiconductor layer, having a greater energy band gap than an adjacent layer of the semiconductor layer

Methodology Applied

Scientific EffectBand gap energy difference:

Implementation Method 2

an active layer on the first optical guide layer

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS7912104B2Semiconductor laser diode

Publication Date: 2011.03.22 LG ELECTRONICS INC

AI summary

A semiconductor laser diode capable of improving reliability and mass-productivity is disclosed. The semiconductor laser diode comprises a first clad layer; a first optical guide layer disposed on the first clad layer; an active layer disposed on the first optical guide layer; a second optical guide layer disposed on the active layer; and a second clad layer disposed on the second optical guide layer, having a greater band gap energy than the second optical guide layer, the band gap energy decreasing as being farther from the second optical guide layer.