GaN/AlN HEMT Structure for Normally-Off Gate Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Developing III-V semiconductor compound-based high electron mobility transistors (HEMTs) faces challenges in improving transistor device performance, particularly in achieving enhanced-mode operation with reduced circuit complexity and cost, while maintaining high electron mobility and frequency transmission capabilities.
Innovation Solution
The semiconductor structure incorporates a heterojunction between undoped gallium nitride (GaN) and aluminum nitride (AlN) layers, with a p-type layer introduced to deplete electrons and create a normally-off carrier channel, enabling enhanced-mode operation by applying a positive gate voltage, and uses intermetallic compounds for improved electrical connections without gold, reducing manufacturing costs and contamination concerns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a heterojunction between undoped GaN and AlN layers is used to form the channel, then electron mobility is enhanced and high-frequency transmission is achieved, but device complexity increases due to the need for precise material composition control
Solution Approach 1:
The patent applies parameter changes by precisely controlling the composition ratio of AlxGa1-xN layers, where the aluminum content parameter x is optimized to achieve the desired balance between electron mobility enhancement and manufacturability. By adjusting the composition parameter within specific ranges, the heterojunction properties are tuned to provide high electron mobility while maintaining practical fabrication capabilities.
Solution Approach 2:
The patent employs composite materials by creating a heterostructure consisting of multiple AlxGa1-xN layers with different aluminum compositions. This composite approach allows the device to leverage the beneficial properties of different material compositions - higher Al content for bandgap engineering and lower Al content for maintaining high electron mobility in the channel region.
2Reliability
If gold is used for intermetallic compounds to improve electrical connections, then electrical conductivity is enhanced, but manufacturing cost increases and contamination concerns arise
Solution Approach 1:
The patent replaces expensive gold with more economical intermetallic compound materials that can provide sufficient electrical connection quality. This substitution reduces manufacturing costs and eliminates the contamination concerns associated with gold, while still achieving reliable electrical connections through the intermetallic compound formation process.
Solution Approach 2:
The patent introduces intermetallic compounds as intermediary materials between the metal electrodes and the semiconductor layers. These intermetallic compounds serve as mediator layers that facilitate reliable electrical connections while being more cost-effective and less problematic than direct gold contacts, addressing both the electrical performance and manufacturing concerns.
3Device complexity
If enhancement-mode operation is implemented to eliminate negative-polarity voltage supply, then circuit complexity is reduced, but achieving normally-off operation requires precise control of the carrier channel depletion
Solution Approach 1:
The patent applies local quality by creating regions with different material compositions and doping characteristics within the device structure. Specifically, the heterojunction interface and the carrier channel region are engineered with localized properties that enable controlled depletion, allowing the device to achieve normally-off operation with precise control over the carrier concentration in specific regions while maintaining simplicity in the overall circuit 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 enhances electron mobility, reduces electron scattering, and achieves cost-effective production of HEMTs with improved gate control and reduced leakage, allowing for efficient high-frequency signal transmission while eliminating the need for negative-polarity voltage supplies.
Implementation Method 1
A p-type layer is disposed on a portion of the second III-V compound layer between the source feature and the drain feature
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 method of forming a high electron mobility transistor (HEMT) includes a first III-V compound layer and a second III-V compound layer disposed on the first III-V compound layer and is different from the first III-V compound layer in composition. A source feature and a drain feature are disposed on the second III-V compound layer. A p-type layer is disposed on a portion of the second III-V compound layer between the source feature and the drain feature. A gate electrode is disposed on the p-type layer. A capping layer is disposed on the second III-V compound layer.