Compressive Strain GaN P-Channel Transistor Hole Mobility

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Solution Overview

Problem

Gallium nitride (GaN) p-channel devices exhibit poor performance and high leakage, limiting their applicability in high-performance applications due to low hole mobility and conductivity, which is exacerbated by the heavy hole/light hole degeneracy, necessitating an enhancement in hole transport mechanisms.

Innovation Solution

Applying uniaxial compressive strain to the GaN p-channel devices by using a source/drain material with a larger lattice constant than the GaN material, which alters the heavy hole bands to resemble light hole bands, thereby reducing the effective mass of holes and enhancing mobility and conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If GaN p-channel devices are used, then high bandgap and high mobility are achieved, but poor performance and high leakage occur due to low hole mobility and conductivity

Engineering Contradiction:

Improvehole mobilityVSAvoiddevice performance

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent applies uniaxial compressive strain to the GaN p-channel device, which changes the physical state of the material by altering the crystal lattice structure. This strain modifies the band structure and reduces the effective mass of holes, thereby increasing hole mobility and improving device performance without changing the fundamental material composition

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If heavy hole/light hole degeneracy is present, then material simplicity is maintained, but hole transport is hindered due to reduced mobility

Engineering Contradiction:

Improvematerial structureVSAvoidhole transport

Core Design Contradiction:

Device complexityVSSpeed

Solution Approach 1:

The patent uses uniaxial compressive strain to change the energy band parameters of the GaN material. The strain lifts the heavy hole/light hole degeneracy by shifting the energy levels, causing the heavy hole band to resemble the light hole band. This parameter change enables faster hole transport while maintaining the simplicity of the single-material structure

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 compressive strain increases hole mobility by a factor of greater than 10, improving the performance of GaN p-channel devices and enabling their use in high-performance applications such as logic and controller circuits by increasing conductivity and reducing leakage.

Implementation Method 1

Applying uniaxial compressive strain to the GaN p-channel devices by using a source/drain material with a larger lattice constant than the GaN material

Methodology Applied

Scientific EffectCompressive strain: Compression

Implementation Method 2

using a source/drain material with a larger lattice constant than the GaN material, which alters the heavy hole bands to resemble light hole bands

Methodology Applied

Scientific EffectLattice constant mismatch: Deformation

Data Source

PatentUS10586866B2Stressors for compressively strained GaN p-channel

Publication Date: 2020.03.10 INTEL CORP

AI summary

Techniques are disclosed for increasing the performance of III-N p-channel devices, such as GaN p-channel transistors. Increased performance is obtained by applying compressive strain to the GaN p-channel. Compressive strain is applied to the GaN p-channel by epitaxially growing a source/drain material on or in the GaN. The source/drain material has a larger lattice constant than does the GaN and puts the p-channel under compressive strain. Numerous III-N material systems can be used.