Bidirectional HEMT with Embedded Reference Electrode
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Solution Overview
Problem
High-frequency power switches require transistors with high breakdown voltage and current density, but existing solutions like field-effect transistors and junction transistors face significant losses and complex gate control circuits, especially for bidirectional operation.
Innovation Solution
A bidirectional heterojunction field-effect power transistor with a dopant implant serving as a reference potential for the control circuit, eliminating the need for Schottky diodes and simplifying gate control, while maintaining high voltage and current handling capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If bidirectional operation is implemented using two normally-off transistors with common drain, then bidirectional current flow is achieved, but gate control circuit complexity increases significantly
Solution Approach 1:
The patent combines two normally-off HEMTs into a single integrated bidirectional device with shared drain and source regions. The gate structures are merged into a unified control mechanism that can simultaneously control both transistor channels, eliminating the need for separate gate control circuits and reducing overall system complexity while maintaining bidirectional functionality.
Solution Approach 2:
The single gate structure performs multiple functions by controlling both transistor channels simultaneously. The gate can regulate current flow in both directions through a unified control mechanism, eliminating the need for separate control circuits for each transistor and simplifying the overall gate control architecture.
2Ease of operation
If Schottky diodes are added for bidirectional operation, then current direction control is improved, but manufacturing complexity and voltage stress increase
Solution Approach 1:
The patent extracts and eliminates the Schottky diode component from the bidirectional switch structure. Instead of adding diodes for current direction control, the invention uses the inherent characteristics of the HEMT structure with properly configured source and drain regions to achieve bidirectional operation, thereby simplifying the manufacturing process and reducing voltage stress on additional components.
Solution Approach 2:
The HEMT structure itself provides the bidirectional current control functionality without requiring external Schottky diodes. The source and drain regions are configured to naturally handle current flow in both directions, and the gate control mechanism automatically regulates current based on the applied voltage polarity, making the system self-sufficient and eliminating the need for additional protective components.
3Strength
If multiple transistors are connected in series for high breakdown voltage, then voltage handling capability is improved, but power losses increase significantly
Solution Approach 1:
The patent merges two HEMT devices into a single integrated structure where the drain of one transistor is directly connected to the source of the other, forming a continuous conduction path. This unified structure reduces the total number of discrete components and interconnections, thereby minimizing parasitic resistances and reducing power losses while maintaining the required breakdown voltage capability through the series configuration of the merged devices.
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 enables efficient bidirectional current operation with reduced bulk and symmetrical behavior, simplifying control and manufacturing, and avoiding the complexity and voltage stress associated with diode-based structures.
Implementation Method 1
Such a transistor consists of two superimposed semiconductor layers with different band gaps, forming a quantum well at their interface. Electrons are confined within this quantum well to form a two-dimensional electron gas.
Implementation Method 2
high-electron-mobility field-effect transistors (HEMTs), also known as heterostructure field-effect transistors (HFETs). Such a transistor consists of two superimposed semiconductor layers with different band gaps, forming a quantum well at their interface.
Implementation Method 3
A bidirectional heterojunction field-effect power transistor with a dopant implant serving as a reference potential for the control circuit
Data Source
Figure 1~4
Figure 5~6
AI summary
The apparatus has a bidirectional hetero-junction field-effect power transistor including a semiconductor layer (4) formed on another semiconductor layer (6). A reference electrode is embedded in the latter semiconductor layer, where a distance between the reference electrode and a conduction electrode (E1) is between 45% and 55% of distance between the conduction electrode and another conduction electrode (E2). A control circuit (9) generates a switching voltage for switching a transistor (1) from a voltage of the reference electrode and applies a control voltage to a gate. The dopant implant is doped with a dopant chosen from a group consisting of Mg, silicon, zinc, chromium, and iron. The latter semiconductor layer is an III-V type group-III nitride semiconductor layer, made of a binary nitride alloy such as gallium nitride alloy. The former semiconductor layer is made of a ternary nitride alloy such as aluminum gallium nitride alloy. The bidirectional hetero-junction field-effect power transistor is a high electron mobility transistor. The reference electrode is a dopant implant (7).