Polarization Compensation Layer in Double Heterojunction FETs

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional heterojunction field-effect transistors face a trade-off between increasing the sheet charge of the two-dimensional electron gas for higher output power and maintaining device reliability, as higher aluminum content in the barrier layer increases strain and reduces reliability, while strain reduction methods like relaxation layers lead to polarization-induced two-dimensional hole gases that decrease sheet charge.

Innovation Solution

Incorporating a polarization compensation layer between the relaxation layer and the channel layer to reduce polarization and prevent the formation of two-dimensional hole gases, allowing for increased aluminum content in the barrier layer and enhanced two-dimensional electron gas sheet charge without compromising reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the aluminum content in the barrier layer is increased to increase the sheet charge of the two-dimensional electron gas, then the output power is improved, but the strain in the device increases and reliability decreases

Engineering Contradiction:

Improveoutput powerVSAvoiddevice reliability

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

A polarization compensation layer is introduced between the barrier layer and the channel layer to compensate for the polarization effect. This intermediary layer reduces the polarization-induced electric field, allowing for higher aluminum content in the barrier layer without creating excessive strain, thus enabling higher sheet charge and output power while maintaining reliability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the material composition parameter by introducing a polarization compensation layer with specific aluminum gallium nitride composition (AlxGa1-xN where 0 < x < 1). This parameter change allows the system to achieve a new balance where high aluminum content in the barrier layer can coexist with reduced net polarization and acceptable strain levels.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a relaxation layer is added to reduce strain, then device reliability is improved, but polarization-induced two-dimensional hole gases form and sheet charge decreases

Engineering Contradiction:

Improvedevice reliabilityVSAvoidsheet charge

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The polarization compensation layer acts as an intermediary that specifically targets and compensates for the polarization effect without introducing the same level of strain as a traditional relaxation layer. This selective compensation reduces polarization-induced hole gases while maintaining acceptable strain levels, preserving sheet charge.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention applies local quality by positioning the polarization compensation layer specifically at the interface where polarization effects are most problematic (between the barrier layer and channel layer), rather than using a broad relaxation layer approach. This localized compensation minimizes the impact on sheet charge while addressing reliability concerns.

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

This approach significantly increases the sheet charge of the two-dimensional electron gas, improving on-state performance and output power while maintaining device reliability by reducing strain and polarization-induced hole gas effects.

Implementation Method 1

The barrier layer is over the channel layer and configured to polarize a junction between the barrier layer and the channel layer to induce a two-dimensional electron gas in the channel layer

Methodology Applied

Scientific EffectPolarization: Polarisation

Implementation Method 2

The polarization compensation layer is between the relaxation layer and the channel layer and configured to reduce a polarization between the relaxation layer and the channel layer

Methodology Applied

Scientific EffectPolarization: Polarisation

Implementation Method 3

The relaxation layer is over the substrate and configured to reduce a strain of the semiconductor device

Methodology Applied

Scientific EffectStrain reduction:

Data Source

PatentUS9972708B2Double heterojunction field effect transistor with polarization compensated layer

Publication Date: 2018.05.15 QORVO US INC

AI summary

A semiconductor device includes a substrate, a relaxation layer, a channel layer, a polarization compensation layer, and a barrier layer. The relaxation layer is over the substrate and configured to reduce a total strain of the semiconductor device. The channel layer is over the relaxation layer. The polarization compensation layer is between the relaxation layer and the channel layer and configured to reduce a polarization between the relaxation layer and the channel layer. The barrier layer is over the relaxation layer and configured to polarize a junction between the barrier layer and the channel layer to induce a two-dimensional electron gas in the channel layer.