Enhancement-Mode HEMT With Segmented AlGaN Barrier
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Solution Overview
Problem
Conventional enhancement-mode high electron mobility transistors (HEMTs) have threshold voltages less than 1 V, limiting their control and on-state resistance, which is similar to depletion-mode HEMTs with unintentionally doped GaN channel layers and AlGaN barrier layers.
Innovation Solution
The development of an enhancement-mode HEMT with a first III-V material layer, a second layer having higher Al content, and a third layer with lower Al content, where the third layer is disposed between the source and drain electrodes, and includes AlzGa(1-z)N with 0.00≤z≤0.10, to achieve a threshold voltage greater than 1 V and similar on-state resistance to depletion-mode HEMTs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional enhancement-mode HEMT structure is used, then device complexity is reduced, but threshold voltage control is insufficient (threshold voltage less than 1 V)
Solution Approach 1:
The barrier layer is segmented into multiple distinct layers with different aluminum compositions. The first barrier layer has a first aluminum composition and the second barrier layer has a second aluminum composition, creating multiple heterojunctions that enable independent control of threshold voltage while maintaining structural organization
Solution Approach 2:
Different regions of the barrier layer are assigned different aluminum compositions to achieve local optimization. The first barrier layer region has specific aluminum content for one function, while the second barrier layer region has different aluminum content for another function, allowing precise local control of electrical properties
2Reliability
If depletion-mode HEMT structure is used, then on-state resistance is improved, but threshold voltage control remains limited
Solution Approach 1:
The barrier structure uses composite material design with two different AlGaN layers having distinct aluminum compositions. This composite structure combines the benefits of low on-state resistance from optimized barrier properties with enhanced threshold voltage control from the multi-layer configuration
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 allows for better control of the HEMT with a threshold voltage greater than 1 V and similar on-state resistance to depletion-mode HEMTs, enhancing the performance of enhancement-mode HEMTs.
Implementation Method 1
a two dimension electron gas is at a heterojunction between a GaN channel layer and an AlGaN barrier layer
Implementation Method 2
A high electron mobility transistor can include a GaN channel layer and an overlying AlGaN barrier layer
Data Source
AI summary
An electronic device can include a transistor. The transistor can include a first layer including a first III-V material, a second layer overlying the first layer and including a second III-V material, and a third layer overlying the first layer and including a third III-V material. In an embodiment, each of the first and second layers includes Al, and the second layer has a higher Al content as compared to the first layer. In another embodiment, the transistor can further include a gate dielectric layer overlying the third layer, and a gate electrode of the transistor overlying the gate dielectric layer and the third layer. The transistor can be an enhancement-mode high electron mobility transistor. The configuration of layers can allow for a relatively higher threshold voltage, as compared to conventional enhancement-mode high electron mobility transistor, to be achieved without significantly affecting RDSON.