Enhancement-mode HEMT with P-doped Functional Layer
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Solution Overview
Problem
Current enhancement-mode HEMTs face manufacturing difficulties and low reliability due to challenges in achieving high hole concentrations in functional layers and precise control of plasma etching, which affects the formation of two-dimensional electron gas (2DEG) and overall electrical performance.
Innovation Solution
An enhancement-mode HEMT device with a gate structure that includes a functional layer of two-dimensional semiconductor material, such as transition-metal dichalcogenide, interposed between the semiconductor body and the gate contact, allowing for direct physical and electrical contact and biasable to control the 2DEG, thereby modifying the energy bands to prevent 2DEG formation without gate voltage, ensuring a normally-off operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a trench gate contact or 2DEG interruption region is used to prevent 2DEG formation, then enhancement-mode operation is achieved, but manufacturing complexity and reliability are reduced
Solution Approach 1:
The patent changes the electrical parameter of the functional layer by introducing high concentrations of acceptor dopants (such as magnesium, zinc, or calcium) to achieve P-type conductivity. This parameter change enables the functional layer to deplete the 2DEG effectively, achieving enhancement-mode operation with reliable performance.
Solution Approach 2:
The patent creates a composite structure by combining the AlGaN barrier layer with a P-type doped functional layer. This composite material approach allows the functional layer to modify the energy bands and prevent 2DEG formation when no gate voltage is applied, while maintaining good ohmic contact when gated.
2Ease of operation
If high hole concentrations are achieved in the functional layer, then 2DEG formation is prevented, but manufacturing precision requirements increase
Solution Approach 1:
The patent performs preliminary doping of the functional layer during the epitaxial growth process, incorporating acceptor dopants directly into the layer formation. This preliminary action ensures high hole concentrations are achieved without requiring complex post-growth doping steps, thereby reducing manufacturing precision requirements.
3Manufacturing precision
If plasma etching is used for precise control, then gate structure fabrication is improved, but manufacturing difficulty increases
Solution Approach 1:
The patent extracts the complex plasma etching step from the manufacturing process by using a growth-based approach where the functional layer is epitaxially grown with built-in P-type doping. This eliminates the need for precise plasma etching to create 2DEG interruption regions, thereby simplifying the overall manufacturing process.
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 solution provides a reliable enhancement-mode HEMT with low power consumption and simplified circuit design, offering improved electrical performances and manufacturing simplicity by using high-doping concentrations in the functional layer to prevent 2DEG formation, ensuring high-quality growth and mechanical performance.
Implementation Method 1
the functional layer is of two-dimensional semiconductor material and includes a first doped portion with P-type electrical conductivity on the top surface of the semiconductor body and is interposed between the semiconductor body and the gate contact along a first axis
Implementation Method 2
The gate structure is biasable to electrically control the 2DEG... high-doping concentrations in the functional layer to prevent 2DEG formation
Data Source
AI summary
An enhancement mode high electron-mobility transistor (HEMT) device includes a semiconductor body having a top surface and including a heterostructure configured to generate a two-dimensional electron gas, 2DEG. The HEMT device includes a gate structure which extends on the top surface of the semiconductor body, is biasable to electrically control the 2DEG and includes a functional layer and a gate contact in direct physical and electrical contact with each other. The gate contact is of conductive material and the functional layer is of two-dimensional semiconductor material and includes a first doped portion with P-type electrical conductivity, which extends on the top surface of the semiconductor body and is interposed between the semiconductor body and the gate contact along a first axis.