Integrated HEM Diode for Overvoltage Protection
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Solution Overview
Problem
Conventional semiconductor diodes with low forward voltages are not suitable for providing overvoltage protection for high electron mobility transistors (HEMTs), leading to the need for external protection diodes that increase system cost.
Innovation Solution
A high electron mobility diode (HEM diode) is integrated on the same semiconductor die as the HEMT, with a control element and specific layer structures to increase the forward voltage, allowing it to provide overvoltage protection without external components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional semiconductor diodes with low forward voltages are used, then the device structure is simple, but the diode cannot provide effective overvoltage protection for HEMT
Solution Approach 1:
The patent combines the HEMT and protection diode onto the same semiconductor die, integrating multiple functions into a single device. This merging eliminates the need for external protection diodes while providing effective overvoltage protection through the specially designed high forward voltage HEM diode structure.
Solution Approach 2:
The patent modifies the forward voltage parameter of the diode by using specific material compositions (AlGaN with varying aluminum content) and structural designs. The diode is engineered to have a forward voltage of 6V or higher, which is sufficient to protect the HEMT from overvoltage conditions while maintaining integration on the same die.
2Reliability
If external protection diodes are connected to HEMT, then overvoltage protection is provided, but system cost increases
Solution Approach 1:
The protection diode and HEMT are manufactured together on the same semiconductor die using a unified fabrication process. This integration eliminates the need for separate external protection diodes and their associated mounting, wiring, and assembly steps, thereby reducing system cost while maintaining overvoltage protection functionality.
3Ease of manufacture
If HEM diode with high forward voltage is integrated on the same die, then system cost is reduced, but device structure becomes more complex
Solution Approach 1:
The patent applies different material compositions and structural characteristics to different regions of the diode to achieve the high forward voltage property. Specifically, the first and second semiconductor layers use different aluminum content ratios in the AlGaN compound, creating localized variations in band structure that collectively produce the desired high forward voltage while maintaining overall structural integration.
4Device complexity
If conventional diodes are used with HEMT, then device structure is simple, but forward voltage is too low for effective protection
Solution Approach 1:
The patent employs composite semiconductor materials, specifically AlGaN layers with different aluminum content ratios, to construct the diode structure. This composite material approach enables the diode to achieve a forward voltage of 6V or higher, which is sufficient for protecting the HEMT from overvoltage conditions, while maintaining compatibility with the HEMT fabrication process.
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 integrated HEM diode offers effective overvoltage protection with a higher forward voltage, reducing system costs and improving performance by eliminating the need for external diodes.
Implementation Method 1
forming an aluminum gallium nitride carrier supply layer on the channel layer wherein a two-dimensional electron gas (2DEG) region is formed near an interface between the channel layer and the carrier supply layer
Data Source
AI summary
In one embodiment, a method of forming a HEM diode may comprise forming the HEM diode with high forward voltage that is greater than one of a gate-to-source threshold voltage of a HEMT or a forward voltage of a P-N diode.