Light Emitting Device Electrode Asymmetry for Forward Voltage

Solution Overview

Problem

Existing light emitting devices face challenges in reducing forward voltage (Vf) while maintaining light emitting intensity distribution, as the number of contact portions and their arrangement significantly impact both forward voltage and light emission efficiency.

Innovation Solution

The light emitting device incorporates a semiconductor layered body with a specific arrangement of n-side and p-side electrodes, including a first n-contact portion and multiple second n-contact portions, where the number and arrangement of these contact portions are optimized to reduce forward voltage and enhance light emitting intensity distribution by adjusting their positions and areas.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the number of n-side contact portions is increased to reduce forward voltage, then the forward voltage decreases, but the light emitting intensity distribution becomes non-uniform

Engineering Contradiction:

Improveforward voltageVSAvoidlight emitting intensity distribution

Core Design Contradiction:

Loss of energyVSIllumination intensity

Solution Approach 1:

The patent applies local quality by making the contact portions have different areas rather than uniform areas. Specifically, the contact portions are designed with larger areas at the peripheral edge portion and smaller areas in the interior region, allowing different regions to serve different functions: peripheral contacts provide low resistance paths for current injection, while interior contacts maintain appropriate current density for uniform light emission.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs asymmetry by creating an asymmetric distribution of contact portion areas across the semiconductor layer. The contact portions are deliberately designed with varying sizes - larger at the periphery and smaller toward the center - breaking the symmetry to optimize both electrical performance (low forward voltage) and optical performance (uniform light distribution).

Inventive Principle:

Principle #4Asymmetry

2Illumination intensity

If the contact portions are arranged to maintain light emitting intensity distribution, then the light emitting uniformity is maintained, but the forward voltage increases

Engineering Contradiction:

Improvelight emitting intensity distributionVSAvoidforward voltage

Core Design Contradiction:

Illumination intensityVSLoss of energy

Solution Approach 1:

The patent applies local quality by making the contact portions have different areas rather than uniform areas. Specifically, the contact portions are designed with larger areas at the peripheral edge portion and smaller areas in the interior region, allowing different regions to serve different functions: peripheral contacts provide low resistance paths for current injection, while interior contacts maintain appropriate current density for uniform light emission.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs asymmetry by creating an asymmetric distribution of contact portion areas across the semiconductor layer. The contact portions are deliberately designed with varying sizes - larger at the periphery and smaller toward the center - breaking the symmetry to optimize both electrical performance (low forward voltage) and optical performance (uniform light distribution).

Inventive Principle:

Principle #4Asymmetry

3Device complexity

If the contact portions are concentrated in one region to reduce manufacturing complexity, then the device complexity decreases, but the light emitting intensity distribution becomes non-uniform

Engineering Contradiction:

Improvecontact portion arrangementVSAvoidlight emitting intensity distribution

Core Design Contradiction:

Device complexityVSIllumination intensity

Solution Approach 1:

The patent applies segmentation by dividing the contact structure into multiple discrete contact portions distributed across different regions of the semiconductor layer, rather than using a single concentrated contact. These segmented contacts are strategically placed at the peripheral edge portion and interior region, with each segment contributing to uniform current distribution and light emission across the device area.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS9614126B2Light emitting device

Publication Date: 2017.04.04 NICHIA CORP

AI summary

A light emitting device includes a light emitting element, a p-side and an n-side post electrode. The light emitting element includes a semiconductor body having n-type and p-type semiconductor layers and a peripheral portion, a first edge, and a second edge. The light emitting element further includes an n-side electrode and a p-side electrode disposed on an insulating film having n-side openings and a p-side opening. The n-side electrode includes second n-contact portions electrically connected to the n-type semiconductor layer through the n-side openings. In a plan view, a p-side post electrode and at least one of the second n-contact portions are at the first edge side. An n-side post electrode electrically connected to the second n-contact portions and at least one of the second n-contact portions are at the second edge side. Fewer second n-contact portions are on the first edge side than that on the second edge side.