U-shape PN Junction JFET for Ultra-High Voltage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High voltage junction field effect transistors (HV JFETs) face challenges in improving performance, particularly in controlling the depletion region size and channel thickness to effectively modulate high-frequency signals and withstand ultra-high voltages.
Innovation Solution
A junction field effect transistor design featuring U-shape PN junctions between the source and drain, with a channel region thickness smaller than the source, and a gate with opposite conductivity type, allowing for precise control of the depletion region and pinch-off of the channel, enabling operation at ultra-high voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the channel thickness is reduced to improve high-frequency signal modulation, then the frequency response is improved, but the voltage withstanding capability deteriorates
Solution Approach 1:
The patent applies different doping concentrations to different regions: the channel region has a first doping concentration while the source and drain regions have a second doping concentration that is higher. This local quality differentiation allows the thin channel to provide good frequency response while the heavily doped source/drain regions provide sufficient voltage withstanding capability through field effect control.
Solution Approach 2:
The patent changes the doping concentration parameter from uniform to non-uniform distribution. By setting the channel doping concentration lower than the source/drain doping concentration, the patent achieves optimal balance between frequency response (requiring thin, lightly-doped channel) and voltage withstanding (requiring heavily doped source/drain regions for field control).
2Power
If the depletion region size is increased to improve voltage control, then the voltage modulation capability is improved, but the on-current deteriorates
Solution Approach 1:
The patent creates a dynamic depletion region that can be precisely controlled through gate voltage. The non-uniform doping profile allows the depletion region to extend effectively into the lightly-doped channel region when needed for voltage control, while the heavily-doped source/drain regions ensure sufficient carrier supply to maintain on-current when the depletion region is retracted.
3Strength
If the source and drain doping concentration is increased to improve voltage withstanding, then the voltage breakdown resistance is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent segments the doping process into distinct regions with different concentrations. The channel region receives a first doping concentration while the source and drain regions receive a second, higher doping concentration. This segmentation can be achieved through standard semiconductor fabrication techniques such as selective epitaxial growth or ion implantation with masking, making the process manageable despite the multiple doping requirements.
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 design achieves a pinch voltage of 1V, a drain current of 6mA at 200V, and a breakdown voltage of 590V, suitable for ultra-high voltage devices, enhancing the performance and reliability of HV JFETs.
Implementation Method 1
The size of a depletion region is controlled by the voltage of the gates, such that the channel can be pitched off and turned off
Implementation Method 2
The first doped region and the second doped region have a U-shape PN junction there between
Data Source
AI summary
A junction field effect transistor is disclosed. The junction field effect transistor includes a first doped region and a second doped region. The first doped region includes a source and a drain. The second doped region includes a gate. The first doped region and the second doped region have a U-shape PN junction there between. The U-shape PN junction is between the source and the drain.