Nitride Semiconductor Electron Barrier Layer Segmentation

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Solution Overview

Problem

Nitride compound semiconductor light-emitting devices face efficiency losses due to charge carriers being lost outside the active layer, primarily due to strong piezoelectric fields generated by lattice mismatch in conventional electron barrier layers, which affect lasing threshold and optical losses.

Innovation Solution

A nitride compound semiconductor device with a p-doped electron barrier layer sequence comprising multiple p-doped layers with decreasing aluminum content, where the first layer has a high aluminum content for a large electronic band gap, reducing piezoelectric fields and mechanical tensions, and ensuring efficient charge carrier injection into the active layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional electron barrier layer with high aluminum content is used, then electron confinement in the active layer is improved, but strong piezoelectric fields are generated causing optical losses

Engineering Contradiction:

Improveelectron confinement efficiencyVSAvoidoptical losses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The electron barrier layer is divided into multiple sub-layers with different aluminum contents. The first sub-layer has high aluminum content (x≥0.5) for strong electron confinement, while the second sub-layer has lower aluminum content (x<0.5) to reduce piezoelectric fields and mechanical tension, thereby reducing optical losses while maintaining electron confinement efficiency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the electron barrier layer are assigned different aluminum contents to optimize local functions. The first sub-layer near the active layer has high aluminum content for maximum electron barrier effect, while the second sub-layer has reduced aluminum content to minimize piezoelectric field generation and associated optical losses in that specific region.

Inventive Principle:

Principle #3Local quality

2Reliability

If a conventional electron barrier layer with high aluminum content is used, then electron confinement is improved, but mechanical tension increases

Engineering Contradiction:

Improveelectron confinement efficiencyVSAvoidmechanical tension

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

The electron barrier layer is segmented into multiple sub-layers with graded aluminum content. The first sub-layer maintains high aluminum content for effective electron confinement, while the second sub-layer uses lower aluminum content to reduce lattice mismatch and consequently reduce mechanical tension in the overall structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The aluminum content parameter is changed across different sub-layers of the electron barrier layer. By gradually reducing the aluminum content from the first to the second sub-layer, the lattice constant changes more gradually, reducing the cumulative mechanical tension while preserving the electron confinement function in the high-aluminum first sub-layer.

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

The solution effectively confines electrons in the active layer, improving injection efficiency and reducing optical losses by minimizing piezoelectric fields and mechanical tensions, thereby enhancing the performance of nitride compound semiconductor devices like LEDs and laser diodes.

Implementation Method 1

the first p-doped layer has an aluminum content x1≥0.5, the first p-doped layer has a large electronic band gap, which forms an advantageously high barrier for electrons

Methodology Applied

Scientific EffectElectronic band gap:

Implementation Method 2

a conventional electron barrier layer generates strong piezoelectric fields due to the great lattice mismatch between the electron barrier layer and the surrounding semiconductor material

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 3

great lattice mismatch between the electron barrier layer and the surrounding semiconductor material

Methodology Applied

Scientific EffectLattice mismatch:

Data Source

PatentUS9634184B2Optoelectronic semiconductor device

Publication Date: 2017.04.25 OSRAM OLED

AI summary

An optoelectronic semiconductor component includes a layer stack based on a nitride compound semiconductor and has an n-type semiconductor region , a p-type semiconductor region and an active layer arranged between the n-type semiconductor region and the p-type semiconductor region. In order to form an electron barrier, the p-type semiconductor region includes a layer sequence having a plurality of p-doped layers composed of AlxInyGa1−x−yN where 0<=x<=1, 0<=y<=1 and x+y<=1. The layer sequence includes a first p-doped layer having an aluminum proportion x1>=0.5 and a thickness of not more than 3 nm, and the first p-doped layer, at a side facing away from the active layer, is succeeded by at least a second p-doped layer having an aluminum proportion x2<x1 and a third p-doped layer having an aluminum proportion x3<x2.