Ridge Semiconductor Structure for Low-Loss Carrier Injection

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Solution Overview

Problem

Existing electro-optical devices with ridge structures face issues of high optical losses, surface recombination, and defect formation due to exposed semiconductor regions and metal fin structures, which hinder efficient carrier injection and laser operation.

Innovation Solution

A trapezoid-shaped semiconductor ridge structure is designed with a capping layer of higher band-gap material covering minimal top surface and a fin structure for continuous electrical contact, reducing surface exposure and enhancing carrier confinement and injection efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a metal fin structure is used for carrier injection, then carrier injection efficiency is improved, but optical losses increase and defect formation occurs

Engineering Contradiction:

Improvecarrier injection efficiencyVSAvoidoptical losses

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

A semiconductor intermediate layer is introduced between the metal contact and the active region, serving as a mediator that enables efficient carrier injection while preventing direct interaction between metal and optical mode, thus reducing optical losses and defect formation

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If the ridge structure has a rectangular shape with exposed top surface, then manufacturing is simplified, but surface recombination increases

Engineering Contradiction:

Improveridge structure fabricationVSAvoidsurface recombination

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The ridge structure is designed with a rounded top surface instead of a sharp rectangular edge, reducing surface recombination sites while maintaining manufacturability through standard epitaxial growth processes

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Reliability

If the capping layer covers the top surface extensively, then surface passivation is improved, but carrier injection is hindered

Engineering Contradiction:

Improvesurface passivationVSAvoidcarrier injection efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The capping layer is applied selectively to different regions of the ridge structure, providing surface passivation on the sides and bottom while leaving the top surface exposed or minimally covered to allow efficient carrier injection from the metal contact

Inventive Principle:

Principle #3Local quality

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 design improves carrier injection, reduces optical losses, and prevents defect formation, leading to enhanced device performance and simplified integration with reduced costs.

Implementation Method 1

The capping layer has a conduction and/or valence band offset, which is sufficiently high to prevent at least one species of charge carriers (e.g., electrons and/or holes) to penetrate into the capping layer and to reach its surface interface

Methodology Applied

Scientific EffectBand-gap energy barrier:

Implementation Method 2

The intermediate region has a trapezoid-shaped top region with a top surface, side surfaces, and inclined surfaces that connect the top surface to the side surfaces

Methodology Applied

Scientific EffectGeometric carrier confinement:

Data Source

PatentUS20250208444A1Electro-optical devices having ridge semiconductor structure and methods of fabricating the same

Publication Date: 2025.06.26 INTERUNIVERSITAIR MICRO ELECTRONICS CENT (IMEC VZW)

AI summary

The disclosed technology generally relates to an electro-optical device based on III-V and/or II-VI and/or group IV semiconductors. In one aspect, the electro-optical device includes a support region and a ridge structure extending from the support region. The ridge structure includes a bottom region provided on the support region and having at least one layer of a first semiconductor material that has a first conductivity type. The ridge structure also includes an intermediate region provided on the bottom region and having an active region. The intermediate region further includes at least one layer of a second semiconductor material, and has a trapezoid-shaped top region with a top surface, side surfaces, and inclined surfaces connecting the top surface to the side surfaces. The ridge structure also includes a capping layer provided on the side surfaces and the inclined surfaces of the intermediate region and having at least one layer of a third semiconductor material that has a higher band-gap than the second semiconductor material. The ridge structure also includes a fin structure extending upwards from the top region and having at least one layer of a fourth semiconductor material that has a second conductivity type.