InGaN Diffusion Barrier for Mg-Doped HEMT Stability
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Solution Overview
Problem
In the development of high electron mobility transistors (HEMTs) using III-V semiconductor compounds, magnesium (Mg) doping leads to diffusion into active layers, affecting the 2-dimensional electron gas (2DEG) and current density, complicating the manufacturing process and reducing device performance.
Innovation Solution
The implementation of an InGaN diffusion barrier layer between the AlGaN and p-GaN layers, which prevents Mg diffusion and enhances the stability of the HEMT device by creating a positive threshold voltage and reducing collisions in the 2DEG channel, thereby improving current density and transistor performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If magnesium (Mg) doping is used to create p-GaN layer, then the device can achieve proper electrical characteristics, but Mg diffuses into active layers and degrades 2DEG and current density
Solution Approach 1:
An InGaN diffusion barrier layer is inserted between the AlGaN layer and the Mg-doped p-GaN layer. This intermediary layer prevents Mg atoms from diffusing into the active AlGaN layer while allowing the p-GaN layer to maintain its electrical characteristics. The barrier layer acts as a mediator that blocks the harmful diffusion path without disrupting the overall device functionality.
2Ease of manufacture
If conventional HEMT structures are used, then manufacturing is simpler, but device performance and stability are reduced due to Mg diffusion effects
Solution Approach 1:
The conventional HEMT structure is segmented by adding an additional InGaN layer between the AlGaN and p-GaN layers. This segmentation divides the structure into distinct functional regions: the AlGaN layer for electron supply, the InGaN barrier layer for diffusion prevention, and the p-GaN layer for electrical control. This segmentation enables precise control over Mg diffusion while maintaining manufacturability.
3Ease of operation
If Mg doping is applied to achieve proper threshold voltage control, then transistor switching is improved, but 2DEG stability and electron mobility are degraded
Solution Approach 1:
The InGaN diffusion barrier layer serves as a mediator that allows the p-GaN layer to perform its threshold voltage control function through Mg doping while preventing the Mg atoms from reaching and destabilizing the 2DEG in the AlGaN layer. The barrier layer decouples the threshold voltage control function from the 2DEG stability requirement.
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 InGaN diffusion barrier layer effectively reduces Mg diffusion, stabilizes the threshold voltage, and increases the mobility of electrons, leading to enhanced performance and reduced manufacturing costs by eliminating the need for gold in metal features, allowing for integration with silicon-fabrication processes.
Implementation Method 1
The implementation of an InGaN diffusion barrier layer between the AlGaN and p-GaN layers, which prevents Mg diffusion
Implementation Method 2
A HEMT is a field effect transistor incorporating a junction between two materials with different band gaps (i.e., a heterojunction) as the channel
Data Source
AI summary
A semiconductor structure includes a first III-V compound layer. A second III-V compound layer is disposed on the first III-V compound layer and is different from the first III-V compound layer in composition. A carrier channel is located between the first III-V compound layer and the second III-V compound layer. A source feature and a drain feature are disposed on the second III-V compound layer. A gate electrode is disposed over the second III-V compound layer between the source feature and the drain feature. A fluorine region is embedded in the second III-V compound layer under the gate electrode. A diffusion barrier layer is disposed on top of the second III-V compound layer. A gate dielectric layer is disposed over the second III-V compound layer. The gate dielectric layer has a fluorine segment on the fluorine region and under at least a portion of the gate electrode.