GaN Bidirectional Switch Layout to Prevent Current Collapse
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lateral nitride semiconductor devices experience current collapse phenomena and characteristic degradation due to high voltage applications, limiting their use in bidirectional switches.
Innovation Solution
A semiconductor device comprising a nitride semiconductor element with a heterojunction, a first and second diode, and p-channel MOSFETs, where the diodes and MOSFETs are connected to maintain equal potential between the substrate and SD electrodes, preventing current collapse by controlling voltage application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high voltage is applied between drain and source in a lateral nitride semiconductor device, then breakdown voltage capability is improved, but current collapse phenomenon occurs causing characteristic degradation
Solution Approach 1:
The device is divided into two separate HEMT structures (first and second HEMTs) with independent gate control, allowing each to operate in opposite polarity modes. This segmentation enables bidirectional voltage blocking capability while maintaining stable current characteristics in each direction through dedicated gate control mechanisms.
Solution Approach 2:
The patent applies reverse gate voltage to prevent current collapse during high voltage operation. By applying a negative voltage to the gate electrode relative to the source, the depletion layer is extended into the channel, preventing carrier accumulation and current collapse phenomena that occur during high voltage stress.
2Reliability
If the back surface is set to the same potential as the source potential to avoid current collapse, then current characteristic stability is improved, but application in bidirectional switches becomes difficult
Solution Approach 1:
The patent creates a universal bidirectional switching device where the same HEMT structure can operate in both forward and reverse polarity modes. By configuring two HEMTs with opposite polarity optimizations and controlling their gates independently, the device achieves multi-functionality as a bidirectional switch capable of blocking and conducting current in both directions with stable characteristics.
Solution Approach 2:
The device employs dynamic gate voltage control to adapt its operation mode. By dynamically adjusting the gate-source voltage polarity and magnitude based on the desired current direction, the device can switch between blocking and conducting states in both polarities, enabling flexible bidirectional operation while maintaining current characteristic stability through active gate management.
3Adaptability or versatility
If lateral structure is used to enable current flow in two directions, then bidirectional current capability is improved, but current collapse phenomenon occurs under high voltage
Solution Approach 1:
The lateral structure is segmented into two independent HEMT units, each optimized for opposite polarity operation. This segmentation allows the device to maintain bidirectional current capability while preventing current collapse in each direction through dedicated gate control mechanisms specific to each HEMT's polarity optimization.
Solution Approach 2:
Each HEMT region is given different local characteristics optimized for its specific polarity operation. The first HEMT is optimized for positive polarity with appropriate doping and structure, while the second HEMT is optimized for negative polarity. This local quality differentiation enables stable bidirectional operation by preventing current collapse in each region through its optimized structure and control.
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 device functions as a low-on-resistance, high-breakdown voltage bidirectional switch, reducing current collapse and ensuring reliable operation under high voltage conditions.
Implementation Method 1
A nitride semiconductor device that uses a nitride semiconductor such as GaN or the like having a heterojunction
Implementation Method 2
a channel formation region in the first nitride semiconductor layer, a gate electrode over the insulating film in the channel formation region
Implementation Method 3
the diodes and MOSFETs are connected to maintain equal potential between the substrate and SD electrodes, preventing current collapse by controlling voltage application
Data Source
AI summary
A semiconductor device includes a nitride semiconductor element, a first diode, and a second diode; the nitride semiconductor element includes a conductive mounting bed, a semiconductor substrate formed on the mounting bed, a first nitride semiconductor layer, a second nitride semiconductor layer, a first major electrode, a second major electrode, a first gate electrode, and a second gate electrode; the first diode includes a first anode electrode electrically connected to the mounting bed, and a first cathode electrode electrically connected to the first major electrode; and the second diode includes a second anode electrode electrically connected to the mounting bed, and a second cathode electrode electrically connected to the second major electrode.