Beta-Ray Emitter Field Effect Transistor for Normally-Off Operation
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Solution Overview
Problem
Field effect transistors, particularly MESFETs, face challenges in achieving a simple power circuit configuration due to the requirement of negative power for depletion mode operation, which complicates the power circuit and limits current driving capacity compared to enhancement mode.
Innovation Solution
Incorporating a channel adjusting member that emits β-particles, such as nickel isotope (Ni-63), tritium (H-3), or strontium isotope (Sr-90), to create a depletion layer in the channel region, allowing for a normally-off operation with a positive gate voltage, simplifying the power circuit and enhancing current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a depletion mode MESFET is used to achieve high current driving capacity, then the current driving capacity is improved, but the power circuit configuration becomes complicated due to requiring negative power
Solution Approach 1:
The patent inverts the conventional approach by using a normally-off enhancement mode MESFET instead of a normally-on depletion mode device. By incorporating a β-ray emitting layer that creates a depletion layer at the channel, the transistor achieves normally-off operation with simple positive power supply, while maintaining high current driving capacity through controlled channel formation.
Solution Approach 2:
The patent changes the operational parameters by introducing a β-ray emitting layer that generates electron-hole pairs in the channel region. This creates a depletion layer that blocks current flow at zero gate voltage, enabling normally-off operation. The gate voltage parameter can then control channel formation by removing or enhancing this depletion layer, achieving both simplicity and high current capacity.
2Device complexity
If an enhancement mode MESFET is used to simplify the power circuit configuration, then the power circuit complexity is reduced, but the current driving capacity decreases
Solution Approach 1:
The patent creates a composite structure by integrating a β-ray emitting layer within the enhancement mode MESFET channel region. This composite material approach combines the simplicity of enhancement mode operation with the high current capacity characteristics, as the β-ray emitting layer modulates carrier concentration to enable controlled channel formation with positive gate voltage.
Solution Approach 2:
The β-ray emitting layer acts as an intermediary that mediates between the gate electrode and the channel region. It converts the gate voltage control into localized carrier generation through β-ray emission, creating a depletion layer that can be dynamically controlled to achieve both simple power circuit operation and high current driving capacity.
3Productivity
If a thicker semiconductor layer is used in depletion mode MESFET to increase current capacity, then the current driving capacity is improved, but the device requires negative power supply which complicates the power circuit
Solution Approach 1:
The patent inverts the conventional depletion mode approach by using enhancement mode operation with a β-ray emitting layer. This allows the use of thicker semiconductor layers for high current capacity while maintaining simple positive power supply requirements, as the β-ray induced depletion layer provides the necessary channel control without requiring negative gate voltages.
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 a field effect transistor with improved electrical properties by allowing a large current flow through the channel, achieving a normally-off state with a positive gate voltage, thus simplifying the power circuit configuration and enhancing operational efficiency.
Implementation Method 1
the depletion layer may be provided by a β-ray emitted from the channel adjusting member
Implementation Method 2
the channel adjusting member emits β-particles to the semiconductor layer
Data Source
AI summary
Provided is a field effect transistor including a semiconductor layer, a gate electrode provided on a channel region in the semiconductor layer, and a channel adjusting member provided adjacent to the channel region on one surface of the semiconductor layer and overlapping the gate electrode on a plane. Here, the channel adjusting member provides a depletion layer in the channel region.