GaN HEMT Layer Structure for Faster Transient Response

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Solution Overview

Problem

Increasing transient response performance in semiconductor devices with high electron mobility transistors (HEMT) containing gallium nitride (GaN) while maintaining crystallinity, as thinning the electron traveling layer can lead to reduced crystallinity and mobility degradation.

Innovation Solution

A semiconductor device structure with a substrate, a buffer layer, a barrier layer with a larger band gap than the buffer and electron traveling layers, and an electron supply layer, where the electron traveling layer is thinner than the buffer layer, utilizing a barrier layer to prevent electron trapping and enhance transient response without compromising crystallinity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the electron traveling layer is made thin to increase transient response performance, then transient response performance is improved, but crystallinity of the channel region and electron supply layer is reduced

Engineering Contradiction:
Improvetransient response performanceVSAvoidcrystallinity
Core Design Contradiction:
SpeedVSStability of the object's composition

Solution Approach 1:

A buffer layer is introduced as an intermediary between the substrate and the electron traveling layer. The buffer layer has a band gap smaller than both the substrate and the electron traveling layer, creating a gradual band gap transition that prevents electron trapping while allowing the electron traveling layer to be thin for high transient response performance.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The band gap parameter is strategically varied across different layers. The buffer layer uses a smaller band gap material to create a favorable band alignment, enabling the electron traveling layer to maintain thin dimensions without causing crystallinity degradation, thus resolving the contradiction between speed and stability.

Inventive Principle:
Principle #35Parameter changes

2Speed

If the electron traveling layer is made thin to improve transient response, then transient response performance increases, but electron mobility characteristics are degraded

Engineering Contradiction:
Improvetransient response performanceVSAvoidelectron mobility characteristics
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The buffer layer acts as a mediator that prevents harmful electron trapping at the substrate-electron traveling layer interface. This allows the electron traveling layer to be thin for high transient response while the buffer layer protects electron mobility characteristics by providing a favorable band alignment that prevents electron energy loss.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 configuration increases transient response performance by preventing electron trapping and maintaining crystallinity, allowing for higher energy electron mobility without the need for thinning the buffer layer, thus enhancing device performance.

Implementation Method 1

a band gap of the barrier layer is larger than a band gap of the buffer layer and a band gap of the electron traveling layer

Methodology Applied
Scientific EffectBand gap energy barrier:

Data Source

PatentEP4401148A1Semiconductor device
Publication Date: 2024.07.17 SUMITOMO ELECTRIC DEVICE INNOVATIONS
  • EP4401148A1 patent drawingFigure 1
  • EP4401148A1 patent drawingFigure 2
  • EP4401148A1 patent drawingFigure 3

AI summary

A semiconductor device of the present disclosure includes a substrate; a buffer layer above the substrate; a barrier layer on the buffer layer; an electron traveling layer on the barrier layer; and an electron supply layer above the electron traveling layer. The electron traveling layer is thinner than the buffer layer. A band gap of the barrier layer is larger than a band gap of the buffer layer and a band gap of the electron traveling layer.