Optically Active Wide-Bandgap Power Transistor for EMI-Immune Switching
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Solution Overview
Problem
Current medium to high voltage power electronics face challenges with complex gate driving schemes, significant electromagnetic interference (EMI), and reliability issues due to the stacking of power transistors, which leads to bulky, expensive, and unreliable systems.
Innovation Solution
The development of optically driven power devices with wide band gap semiconductor structures, featuring optically active channels and regions, allows for direct optical control, eliminating the need for complex electrical drivers and enhancing EMI immunity by using heterogeneous integration of narrow band gap materials with wide band gap semiconductors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If power transistors are stacked serially to achieve high voltage blocking capabilities, then the blocking voltage increases, but the device complexity and gate driving scheme complexity increase significantly
Solution Approach 1:
The patent replaces electrical gate driving with optical control. Specifically, it uses a laser diode to optically control the channel conductivity of a field-effect transistor, eliminating the need for complex electrical gate driving circuits. The optical control signal modulates the channel current directly, simplifying the control system while maintaining high voltage blocking capability through the drift region structure.
Solution Approach 2:
The patent introduces an optical intermediary (laser diode and optical signal) between the control system and the power transistor. The optical signal serves as a mediator that controls the channel conductivity without direct electrical connection, thereby simplifying the gate driving scheme and providing galvanic isolation between the control and power circuits.
2Strength
If power transistors are stacked serially for high-voltage operation, then the blocking voltage increases, but electromagnetic interference increases significantly
Solution Approach 1:
The patent substitutes electrical control signals with optical control signals. The laser diode generates optical signals that control the channel conductivity, replacing electrical gate signals. This substitution eliminates electromagnetic interference associated with electrical gate driving while maintaining the high voltage blocking capability through the optimized drift region and optical control mechanism.
3Strength
If power transistors are stacked serially to achieve high voltage capabilities, then the blocking voltage increases, but the system becomes bulky and expensive
Solution Approach 1:
The patent replaces complex electrical stacking arrangements with a simplified optical control architecture. A single field-effect transistor with optical control can achieve high voltage blocking capabilities without requiring multiple stacked transistors and their associated complex electrical interconnections. This reduces system size, component count, and overall cost while maintaining the required blocking voltage.
Solution Approach 2:
The optically controlled field-effect transistor serves multiple functions simultaneously: it provides high voltage blocking capability through its drift region structure, current conduction through the channel, and optical control sensitivity through the optically active channel material. This multi-functionality eliminates the need for separate control circuits and stacked transistor arrangements, reducing system complexity and size.
4Ease of operation
If conventional optically triggered devices use phototransistors to drive power switches indirectly, then optical control is achieved, but the advantages of direct optical control are not fully utilized
Solution Approach 1:
The patent implements direct optical control by making the channel itself optically active, eliminating the need for intermediate phototransistors. The channel material (such as InGaAs or InGaSb) directly converts optical signals into channel conductivity changes, providing a straightforward optical-to-electrical conversion pathway without indirect control stages. This direct control approach simplifies the device structure and fully utilizes the advantages of optical 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
This approach results in simpler, more compact, and cost-effective driver circuits for high-voltage applications, achieving high current densities and improved reliability with enhanced EMI immunity, enabling efficient high-voltage power systems.
Implementation Method 1
the optically active material generates charge carriers in response to an optical signal
Implementation Method 2
a drift region comprising a wide band gap material that produces or absorbs reactive power to maintain a voltage when the semiconductor power device is in an off state
Data Source
AI summary
Described herein is a semiconductor structure, comprising: a drain region; a drift region comprised of a wide band gap material disposed over the drain region; and a channel structure disposed over the drift region. In some embodiments, the channel structure comprises: an optically active material disposed over the drift region, wherein the optically active material generates charge carriers in response to an optical signal; and a source region disposed over the optically active material, wherein in an off state charge carriers in the optically active material are depleted to turn off the semiconductor structure, and in an on state charge carriers in the optically active material conduct a current in the semiconductor structure when an electric field is applied across the source region and drain region, causing the current to substantially flow directly between the source region and the drain region.