GaN HEMT Gate Structure for Impact Energy Release in Irradiation
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Solution Overview
Problem
GaN HEMT transistors lack avalanche capability, leading to device failure and reliability issues in aerospace irradiation environments due to the inability to release impact energy during switching processes.
Innovation Solution
An asymmetric multi-integrated gate structure GaN HEMT transistor is developed, featuring an Ohmic metal pillar with a main pillar and auxiliary pillars, which effectively releases impact energy by its proximity to the GaN channel and maintains polarization function to ensure forward current capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If Schottky gate contacts are used to reduce gate leakage current, then gate leakage is reduced, but the Schottky barrier prevents energy release from gate-drain capacitance during switching
Solution Approach 1:
The gate contact structure is segmented into multiple components: Schottky gate contacts for leakage reduction, Ohmic metal pillars for energy release, and auxiliary pillars for enhanced energy dissipation. This segmentation allows each component to fulfill its specific function without interfering with others.
Solution Approach 2:
Ohmic metal pillars are introduced as intermediary structures between the Schottky gate contacts and the GaN channel. These pillars provide a dedicated pathway for energy release from gate-drain capacitance during switching, mediating between the need for low leakage and the need for energy dissipation.
2Device complexity
If GaN HEMT lacks avalanche capability, then device structure is simpler, but transistor cannot release transient energy impact and suffers catastrophic failure in radiation environments
Solution Approach 1:
Ohmic metal pillars and auxiliary pillars are pre-positioned within the device structure before operation. These structures are prepared in advance to provide energy release pathways, ensuring that when transient energy impact occurs during switching or radiation exposure, the energy can be immediately dissipated through the pre-configured pillar structures.
Solution Approach 2:
The auxiliary pillars act as cushioning structures that absorb and dissipate excess energy before it can cause catastrophic damage to the main transistor structure. This beforehand cushioning protects the device against transient energy impacts and radiation-induced stress.
3Loss of energy
If asymmetric multi-integrated gate structure with Ohmic metal pillars is introduced for energy release, then impact energy release capability is improved, but device structure becomes more complex
Solution Approach 1:
The gate structure employs local quality differentiation with main Ohmic metal pillars having different dimensions and positions compared to auxiliary pillars. Each pillar type is optimized for its specific location and function, with local variations in geometry and material properties to maximize energy release efficiency while maintaining overall structural coherence.
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 asymmetric multi-integrated gate structure allows for efficient release of impact energy, enhancing the robustness of the gate and maintaining the forward current capability, thereby improving the reliability and radiation resistance of GaN HEMT transistors in aerospace environments.
Implementation Method 1
GaN HEMTs prepared based on AlGaN/GaN heterojunctions are unable to form a body diode inside the transistor, and cannot maintain and release transient energy impact using the avalanche breakdown characteristics of the body diode
Implementation Method 2
the enhanced gallium nitride-based high-electron-mobility transistor (HEMT), representative of the existing technology, often uses Schottky gate contacts, which significantly reduce gate leakage current. However, the Schottky barrier, due to its rectifying effect, limits the flow of electrons from the gate to the metal above the gate
Implementation Method 3
the first auxiliary pillar on the left side plays an important role in maintaining the polarization effect of the AlGaN/GaN layer and minimizing the impact on the forward current capability between the gate and source
Data Source
AI summary
The present invention discloses a GaN HEMT transistor with impact energy release capability for use in aerospace irradiation environment and preparation method thereof. The transistor includes a substrate layer, a gallium nitride layer, a barrier layer, and a gate structure successively arranged from bottom to top. The gallium nitride layers on both sides of the barrier layer are respectively provided with a source electrode and a drain electrode on the top surface. The gate structure is located near the source electrode and includes a p-type gallium nitride layer, a dielectric layer, an Ohmic metal pillar, and a Schottky metal layer. The present invention solves the breakdown problem caused by the inability to release impact energy during the switching process by introducing an asymmetric multi-integrated gate structure.