GaN Switching Transistor Reducing Signal Distortion
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Solution Overview
Problem
Existing high frequency switches, such as those used in communication terminals, face challenges in minimizing signal distortion and loss, particularly with the increasing number of frequency bands used in carrier aggregation, which degrades transmission capacitance and introduces harmonic distortion.
Innovation Solution
A switching transistor with a channel layer and barrier layer formed using compound semiconductors, achieving a sheet electron density of at least 1.7×10^13 cm^-2, and a MIS gate structure to modulate electron density and reduce distortion, along with an ohmic metal layer to improve contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If use of an SOI substrate is implemented to reduce parasitic capacitance, then loss is reduced, but signal distortion is not sufficiently suppressed
Solution Approach 1:
The invention changes the material parameters by using compound semiconductor layers (such as GaN and AlGaN) with specific compositional ratios and thicknesses. The channel layer has a specific electron concentration range (1×10^17 to 1×10^19 cm^-3) and the barrier layer has a controlled aluminum composition ratio (0.2 to 0.5), which together achieve both low loss and low distortion by optimizing the electronic properties of the semiconductor structure
Solution Approach 2:
The invention employs a composite semiconductor structure consisting of multiple layers with different material compositions - a channel layer made of GaN or InGaN, a barrier layer made of AlGaN, and optionally a buffer layer. This composite structure leverages the complementary properties of each material to simultaneously reduce parasitic capacitance (lowering loss) and suppress signal distortion
2Object-generated harmful factors
If the sheet electron density of the channel layer is increased to reduce high frequency distortion, then distortion is suppressed, but device complexity increases
Solution Approach 1:
The invention achieves high sheet electron density (≥1.7×10^13 cm^-2) by controlling the electron concentration in the channel layer within a specific range (1×10^17 to 1×10^19 cm^-3) and optimizing the barrier layer thickness (5 nm to 50 nm). This parameter optimization reduces high frequency distortion without requiring complex device architectures
Solution Approach 2:
The invention replaces complex mechanical or structural solutions with a field-based approach by utilizing the quantum mechanical effect of two-dimensional electron gas formation at the AlGaN/GaN interface. This natural physical phenomenon generates the required high electron density without additional structural complexity
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 effectively suppresses signal distortion and reduces on-resistance, achieving low loss and low distortion characteristics suitable for high frequency applications, enhancing the switching transistor's performance in communication terminals.
Implementation Method 1
a two-dimensional electron gas formed in the channel layer has the high sheet electron density equal to or higher than 1.7×10^13 cm−2. Here, high frequency distortion becomes smaller as the sheet electron density of a channel becomes higher.
Data Source
AI summary
[Overview] [Problem to be Solved] To provide a switching transistor and a semiconductor module having lower distortion generated in a signal. [Solution] A switching transistor including: a channel layer including a compound semiconductor and having sheet electron density equal to or higher than 1.7×1013 cm−2; a barrier layer formed on the channel layer by using a compound semiconductor that is of a different type from the channel layer; a gate electrode provided on the barrier layer; and a source electrode and a drain electrode provided on the barrier layer with the gate electrode interposed between the source electrode and the drain electrode.