Nitride LED Current Spreading Layer Design

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Solution Overview

Problem

Conventional nitride LEDs experience current crowding due to high electrical current density, which limits light output efficiency and results in uneven current distribution.

Innovation Solution

A compound dual current spreading layer is introduced, comprising a first distributed insulating layer formed by ion implantation and a second interlaced layer of undoped and n-type nitride semiconductor layers, with a gradient-doped n-type layer to repair defects and guide current, ensuring uniform current distribution across the light-emitting area.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional nitride LED structure is used, then manufacturing is simpler, but current crowding occurs and light output efficiency is limited

Engineering Contradiction:

Improvelight output efficiencyVSAvoidcurrent spreading layer structure

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The current spreading layer is divided into multiple functional sub-layers: a first current spreading layer with distributed insulating portions to break up current paths, a second current spreading layer with interlaced undoped and n-type nitride semiconductor layers for lateral current spreading, and a gradient-doped n-type layer to repair defects. This segmentation allows each sub-layer to address specific aspects of current distribution, effectively reducing current crowding and enhancing light output efficiency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The current spreading layer employs composite material structures combining different nitride semiconductor layers with varying doping concentrations (undoped, n-type, and gradient-doped regions). This composite approach leverages the complementary properties of each material region: undoped layers for defect reduction, n-type layers for carrier injection and lateral spreading, and gradient-doped layers for defect repair, collectively achieving superior current distribution and light output efficiency.

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If ion implantation is used to form distributed insulating portions, then current distribution improves, but defects are introduced in the first layer

Engineering Contradiction:

Improvecurrent distribution uniformityVSAvoidlayer defect density

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The gradient-doped n-type nitride semiconductor layer is inserted between the first and second current spreading layers to proactively repair defects caused by ion implantation before the second layer is formed. This preliminary defect repair action ensures that subsequent layers are grown on a healthier substrate, maintaining high current distribution uniformity while mitigating the harmful effects of ion implantation-induced defects.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The gradient-doped n-type layer converts the harmful effects of ion implantation-induced defects into a beneficial process by using the gradient doping profile to gradually heal lattice damage and reduce dislocation density. The gradient doping acts as a self-repair mechanism that transforms the damaged region into a improved structure, enhancing overall layer quality while preserving the current distribution benefits of ion implantation.

Inventive Principle:

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

3Productivity

If the current spreading layer is made thicker, then current spreading capability improves, but manufacturing precision and defect repair become more difficult

Engineering Contradiction:

Improvecurrent spreading capabilityVSAvoidlayer thickness control

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The current spreading layer is segmented into multiple thin sub-layers with specific thickness ranges: the first current spreading layer is 100-5000 Å, the gradient-doped n-type layer is 200-5000 Å, and the second current spreading layer is 700-10,000 Å. This segmentation into manageable thicknesses enables precise control of each layer during manufacturing while collectively achieving the desired current spreading capability through the combined effect of all sub-layers.

Inventive Principle:

Principle #1Segmentation

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 reduces current crowding, enhances light output efficiency by up to 20%, and increases the static breakdown voltage of the LED.

Implementation Method 1

the distributed insulating portions are formed by ion implantation

Methodology Applied

Scientific EffectIon implantation: Ion Implantation

Implementation Method 2

the gradient-doped n-type nitride semiconductor layer is formed by secondary growth of epitaxy

Methodology Applied

Scientific EffectEpitaxy: Epitaxy

Data Source

PatentUS8860044B2Nitride light-emitting diode with a current spreading layer

Publication Date: 2014.10.14 QUANZHOU SANAN SEMICON TECH CO LTD

AI summary

A nitride light-emitting diode is provided including a current spreading layer. The current spreading layer includes a first layer having a plurality of distributed insulating portions configured to have electrical current flow therebetween; and a second layer including interlaced at least one substantially undoped nitride semiconductor layer and at least one n-type nitride semiconductor layer configured to spread laterally the electrical current from the first layer.