GaN HEMT Moat Structure for Heat and Field Control
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Solution Overview
Problem
High electron mobility transistors (HEMTs) face reliability issues due to heat effects during high-frequency operations, which affect the quality and performance of GaN-based HEMTs, primarily because of the high electric current and generated heat at the channel.
Innovation Solution
Incorporating a moat in the second III-V compound layer to control the distribution of two-dimensional electron gas (2DEG) and electric fields, enhancing the electrical performance and reliability of HEMTs by using a first and second moat disposed between the source and drain electrodes, respectively, within the second III-V compound layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high electric current is used during high frequency operations, then switching velocity is enhanced, but heat effect is generated at the channel
Solution Approach 1:
The patent extracts the harmful heat effect from the channel region by introducing a moat structure that removes excess heat away from the active channel, allowing high current operation without excessive temperature rise
Solution Approach 2:
The moat structure acts as an intermediary thermal management element between the heat-generating channel and the surrounding environment, facilitating heat dissipation while maintaining the high current necessary for fast switching
2Quantity of substance
If high electric current is used during high frequency operations, then electron density of 2DEG is increased, but reliability of HEMT is lowered
Solution Approach 1:
The patent converts the harmful effect of high current operation into a benefit by using the moat structure to manage the associated heat and reliability issues, allowing the high electron density necessary for fast switching while maintaining device reliability through improved thermal management
3Stability of the object's composition
If moat is formed in second III-V compound layer, then electric field distribution is controlled, but device complexity is increased
Solution Approach 1:
The moat structure introduces local variations in the second III-V compound layer, creating specific regions with different electrical properties that control the electric field distribution locally without requiring complex changes to the entire device structure
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 moat structure improves the stability of the threshold voltage, reduces hysteresis, and enhances the breakdown voltage of HEMTs, thereby improving the overall electrical performance and reliability by controlling 2DEG and electric field distribution.
Implementation Method 1
Two-dimensional electron gas (2DEG) may be generated by the piezoelectricity property of the GaN-based materials
Data Source
AI summary
A high electron mobility transistor includes a first III-V compound layer, a second III-V compound layer, a source electrode, a drain electrode, a gate electrode, a first moat, and a second moat. The second III-V compound layer is disposed on the first III-V compound layer. The source electrode and the drain electrodes are disposed above the first III-V compound layer. The gate electrode is disposed above the second III-V compound layer located between the source and the drain electrodes in a first direction. The second III-V compound layer includes a first region under the gate electrode. The first moat is at least partially disposed between the first region and the source electrode in the first direction. The second moat is at least partially disposed between the first region and the drain electrode in the first direction.