Graded Barrier Heterojunction Structure for Higher 2DEG Current
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Solution Overview
Problem
Conventional transistors using silicon face limitations in power efficiency and heat generation due to restricted current flow and electron mobility, which can be improved by utilizing wider bandgap semiconductor materials in heterojunction structures.
Innovation Solution
A heterojunction structure is developed where the barrier semiconductor layer is epitaxially grown on a channel semiconductor layer with varying element composition, enhancing free electron density and mobility, thereby increasing current flow and reducing on-resistance and heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional silicon transistors are used, then manufacturing is well-established and reliable, but power efficiency is limited and heat generation is high due to restricted current flow and electron mobility
Solution Approach 1:
The patent changes the material parameters by transitioning from silicon to wider bandgap semiconductor materials (GaN, AlGaN) and modifies the compositional parameters through varying aluminum content in the barrier layer. This enables higher electron mobility and better power efficiency while managing the increased manufacturing complexity through controlled composition gradients
Solution Approach 2:
The patent employs composite heterojunction structures combining different semiconductor materials (GaN channel layer with AlGaN barrier layer) to achieve superior electrical properties. The composite structure leverages the advantages of each material to improve power efficiency and reduce energy loss
2Productivity
If uniform composition barrier layer is used, then manufacturing process is simple, but free electron density and current flow are limited
Solution Approach 1:
The patent applies local quality by varying the aluminum composition specifically in the barrier layer while keeping the channel layer uniform. This localized compositional variation optimizes electron density and current flow in the critical barrier region without complicating the entire structure
Solution Approach 2:
The patent introduces dynamic composition grading in the barrier layer, transitioning from uniform to graded aluminum content. This dynamic approach allows optimization of electron transport properties throughout the barrier layer thickness, enhancing current flow capability
3Reliability
If higher electron mobility is achieved through material composition, then on-resistance decreases and power efficiency improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent carefully controls epitaxial growth parameters including temperature, pressure, and gas flow rates to achieve precise composition gradients. By optimizing these process parameters, high manufacturing precision is maintained while achieving the desired electron mobility and device reliability
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 allows for greater current flow at a given voltage and improved power efficiency, reducing on-resistance and heat generation in transistors, specifically in High Electron Mobility Transistors (HEMTs) using materials like GaN and AlGaN.
Implementation Method 1
a barrier semiconductor layer epitaxially grown on a channel semiconductor layer
Data Source
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AI summary
A heterojunction structure in which a barrier semiconductor layer is epitaxially grown on a channel semiconductor layer but varying a composition of the barrier semiconductor layer for at least part of the epitaxial growth of the barrier semiconductor layer. By so doing, in some cases, a free electron density in planar view of the 2DEG may be increased thereby allowing for greater current flow for a given voltage difference. Furthermore, for a given current, the mobility of the electrons is increased, thus reducing the on resistance of transistors that include the 2DEG as a channel region. This further improves power efficiency of the transistor, and reduces heat generated by the transistor at a given power.