Segmented Anode NPNP Trench Device Low Voltage Conduction
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Solution Overview
Problem
Existing npnp and pnpn layered structures in insulated-gate power devices require higher operating voltages to conduct significant current, limiting their efficiency and applicability in low-voltage applications.
Innovation Solution
A composite anode design is introduced, featuring a segmented p-type layer with gaps containing n-type semiconductor material, allowing for direct majority carrier current flow between the anode and n-type collector, thereby reducing the minimum operating voltage and enabling current conduction at voltages as low as 0 volts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional p-type anode layer is used in npnp layered structures, then the device structure is simple and continuous, but the minimum operating voltage is high (above 1.0 volt) and significant current cannot be conducted at low voltages
Solution Approach 1:
The continuous p-type anode layer is divided into multiple discrete p-type regions separated by n-type regions. This segmentation creates multiple independent current paths, allowing current to flow through n-type regions at low voltages while maintaining the bipolar regenerative action through p-type regions at higher voltages, thereby reducing the minimum operating voltage from above 1.0V to as low as 0V
Solution Approach 2:
The anode structure is transformed from a single p-type material layer into a composite structure containing alternating p-type and n-type semiconductor regions. This composite design enables the device to exhibit both MOSFET-like low-voltage conduction through n-type regions and bipolar transistor action through p-type regions, achieving low minimum operating voltage while maintaining high current capability
2Loss of energy
If npnp layered structure with bipolar action is used, then efficiency is improved and forward voltage is lower than MOSFET, but the device cannot conduct significant current at voltages below 1.0 volt
Solution Approach 1:
By segmenting the anode into discrete p-type regions separated by n-type regions, the invention creates parallel conduction paths. The n-type regions enable current flow at low voltages (0-1V) through majority carrier conduction, while the p-type regions maintain bipolar regenerative action at higher voltages, thus enabling significant current conduction below 1.0V while preserving low forward voltage drop characteristics
Solution Approach 2:
The segmented anode structure provides multi-functionality: n-type regions serve as low-voltage conduction paths enabling operation down to 0V, while p-type regions maintain the bipolar transistor action for efficient high-current conduction. This universal design allows the device to operate efficiently across the entire voltage range from 0V to high voltages, combining advantages of both MOSFET and bipolar transistor operation
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 composite anode design allows for efficient current conduction at lower operating voltages, improving device efficiency and enabling the use of npnp IGTO devices in applications requiring low voltage operation without compromising breakdown voltage or regenerative action at higher voltages.
Implementation Method 1
allowing for direct majority carrier current flow between the anode and n-type collector
Implementation Method 2
When the anode-cathode voltage increases above about 1.0 volts, the gaps in the segmented p-type anode layer continue to conduct current, but the main current path through the npnp structure turns on (due to regenerative action) to conduct a majority of the device's current
Data Source
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AI summary
An npnp layered switch is modified to have a composite anode structure. Instead of the continuous p-type bottom anode layer of a typical npnp IGTO device, thyristor, or IGBT, the composite anode is formed of a segmented p-type layer with gaps containing n-type semiconductor material. The n-type material forms a majority carrier path between the bottom anode electrode and the n- type collector of the vertical npn bipolar transistor. When a trenched gate is biased high, the majority carrier path is created between the bottom anode electrode and the top cathode electrode. Such a current path operates at very low operating voltages, starting at slightly above 0 volts. Above operating voltages of about 1.0 volts, the npnp layered switch operates normally and uses regenerative bipolar transistor action to conduct a vast majority of the current. The two current paths conduct in parallel.