Breakdown Voltage Enhancement in AlGaN/GaN High-Electron Mobility Transistor by Optimizing Gate Field-Plate Structure

Area of Science:

• Materials Science
• Electrical Engineering
• Semiconductor Physics

Background:

• AlGaN/GaN high-electron mobility transistors (HEMTs) are crucial for power electronics.
• Improving breakdown voltage is essential for device reliability and performance.
• Electric field spikes near gate edges limit device performance.

Purpose of the Study:

• To optimize gate head structures for enhanced breakdown voltage in AlGaN/GaN HEMTs.
• To investigate the impact of T-shaped gate-connected field-plates (FPs) on device characteristics.
• To determine the optimal configuration and dimensions of FPs and passivation layers.

Main Methods:

• Utilized a two-dimensional device simulator.
• Investigated various T-shaped gate-connected field-plate configurations.
• Analyzed the effect of field-plate extension (source, drain, symmetric) and passivation layer thickness.

Main Results:

• The T-shaped gate-connected field-plate effectively alleviates electric field spikes.
• Extending the FP towards the drain achieved the highest breakdown voltage (224 V).
• Optimum FP length was 2 μm, with a maximum transconductance of 132.5 mS/mm.
• Optimum Si₃N₄ passivation layer thickness was determined to be 50 nm.

Conclusions:

• T-shaped gate-connected FPs are effective in improving breakdown voltage of AlGaN/GaN HEMTs.
• Field-plate extension towards the drain offers superior performance.
• Device optimization involves careful tuning of FP geometry and passivation layer thickness.