Heterojunction Channel Doping for Linear GaN HEMT Power Devices
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Solution Overview
Problem
Traditional AlGaN/GaN-based HEMT structures face challenges with high electron mobility and saturation rate due to high 2DEG concentration at the heterojunction interface, leading to nonlinear transmission characteristics and signal distortion at high frequencies and high power applications.
Innovation Solution
A semiconductor structure with a heterojunction including a channel layer and a barrier layer, where the channel layer has multiple n-type doped layers with varying doping concentrations and thicknesses, and at least one n-type doped layer is a wide bandgap semiconductor layer with graded In element content, improving electron distribution and linearity by adjusting the energy band structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the 2DEG concentration at the AlGaN/GaN heterojunction interface is increased to achieve high output power, then the power capability is improved, but the electron mobility and saturation rate decrease due to high carrier concentration, resulting in nonlinear transmission characteristics and signal distortion
Solution Approach 1:
The channel layer is divided into multiple segments with different doping concentrations (first doped region with concentration N1, second doped region with concentration N2 where N1 < N2). This segmentation creates a gradient structure that distributes electron concentration more evenly, preventing the excessive 2DEG accumulation at the interface while maintaining high power capability and improving linearity.
Solution Approach 2:
Different regions of the channel layer are assigned different doping concentrations to achieve local optimization. The first doped region closer to the heterojunction interface has lower doping concentration to reduce 2DEG accumulation and improve linearity, while the second doped region has higher doping concentration to maintain high power output capability.
2Power
If the 2DEG concentration is increased to improve power capability, then the power output is enhanced, but the electron mobility decreases due to carrier-carrier scattering and impurity scattering
Solution Approach 1:
The channel layer is segmented into multiple doped regions with different doping concentrations. This segmentation allows electrons to experience lower scattering rates in the first doped region (N1) while still accessing high carrier density regions (N2) for power generation, thereby maintaining electron mobility while preserving power capability.
Solution Approach 2:
The doping concentration parameter is changed spatially across the channel layer, transitioning from lower concentration (N1) near the interface to higher concentration (N2) in the second doped region. This parameter variation optimizes the balance between electron mobility and power capability by reducing carrier-carrier scattering in critical regions.
3Speed
If traditional AlGaN/GaN HEMT structure is used to achieve high frequency performance, then the frequency response is improved, but the transconductance presents typical peak characteristics causing signal distortion
Solution Approach 1:
The channel layer is segmented into multiple doped regions that modify the transconductance characteristic from peak-type to more uniform response. This segmentation creates a distributed electron concentration profile that smooths the transconductance curve, reducing signal distortion while maintaining high frequency response capability.
Solution Approach 2:
Different doping concentrations are applied in different channel regions to locally control the electric field distribution and carrier concentration. This local quality variation eliminates the peak characteristics in transconductance by creating a more uniform electron distribution across the channel, thereby improving signal fidelity.
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 enhances the linearity of the semiconductor structure under high field conditions, reducing device degradation and signal distortion, and improves electron mobility by forming a more uniform electron concentration and three-dimensional electron gas, thereby improving the performance of high-frequency and high-power microwave devices.
Implementation Method 1
The two-dimensional electron gas (2DEG) formed by HEMT has high mobility
Implementation Method 2
adjusting the energy band structure... forming a more uniform electron concentration and three-dimensional electron gas
Data Source
AI summary
A semiconductor structure and a manufacturing method thereof are provided in the present application provides. The semiconductor structure includes a substrate and a heterojunction structure located on the substrate. The heterojunction structure includes a channel layer and a barrier layer located on the channel layer. The channel layer includes at least one n-type doped layer. The manufacturing method of the semiconductor structure includes: providing a substrate; forming a heterojunction structure on the substrate, where forming the heterojunction structure includes: forming a channel layer on the substrate, doping the channel layer to form an n-type doped layer; forming a barrier layer on the channel layer; forming a gate electrode, a source electrode and a drain electrode, the gate electrode is located on the heterojunction structure, and the source electrode and the drain electrode are located on two sides of the grid electrode, separately.