Behind the Paper

Stability Analysis of p-GaN Gate AlGaN/GaN HEMTs Under High Voltage Stress

GaN power transistors are vital for efficient energy systems. However, their threshold voltage instability under stress hinders reliability. Our study reveals the recoverable nature of this shift in p-GaN gate HEMTs, providing key design insights for stable power chips.
Moore and More Jan 28, 2026

The reliability of gallium nitride (GaN)-based high-electron-mobility transistors (HEMTs) is critical for their adoption in high-power applications such as electric vehicles, 5G infrastructure, and renewable energy systems. Among these devices, p-GaN gate HEMTs have emerged as promising candidates for enhancement-mode operation. However, their long-term stability under extreme electrical stress remains a key concern. This study systematically investigates the threshold voltage (VTH) instability of p-GaN gate AlGaN/GaN HEMTs under static and dynamic drain stress, providing actionable insights for device optimization.

 Key Experimental Findings

  1. VTH Shift Under Drain Stress
  • Pulsed I-V measurements revealed a significant positive VTH shift (ΔVTH ) as drain voltage increased from 0 V to 650 V, with a maximum ΔVTH of 0.7 V observed.
  • At 200 V drain bias, ΔVTH reached 0.4 V but saturated under prolonged stress, indicating a self-limiting degradation mechanism.
  1. Recovery Dynamics
  • Post-stress recovery analysis demonstrated that ΔVTH gradually diminished after stress removal. At 300 V, an initial rapid recovery was followed by a negative ΔVTH shift, attributed to electron injection via gate-drain capacitance (CGD).
  • Temperature-dependent studies (25–150℃) showed accelerated ΔVTH recovery at elevated temperatures, with 150℃ conditions reducing recovery time by over 60% compared to room temperature.
  1. Mechanistic Insights
  • The instability originated from hole depletion in the p-GaN layer under high electric fields. Stress removal allowed hole replenishment through capacitor discharge, mitigating VTH shifts.
  • No permanent degradation was observed, confirming the robustness of p-GaN gate structures under transient stress conditions.

 

Technological Implications

The findings directly address a critical barrier to GaN power device commercialization. By elucidating the interplay between electrical stress, temperature, and recovery kinetics, this work enables:

  • Circuit-Level Solutions: Integration of passive components with p-GaN HEMTs to stabilize VTH in high-voltage environments.
  • Thermal Management Strategies: Leveraging temperature-accelerated recovery for system design optimization.
  • Reliability Prediction Models: Data-driven frameworks to forecast device lifetimes under real-world operating conditions.

 

Challenges and Future Directions

While the study establishes foundational knowledge, several challenges remain:

  1. Material-Level Optimization:Further reduction of interface trap densities in p-GaN/AlGaN heterostructures.
  2. System Integration:Development of compact models incorporating stress-dependent parameters for circuit simulation.
  3. Standardized Testing Protocols: Establishment of industry benchmarks for dynamic stress characterization.

Future research should prioritize hybrid approaches combining device physics insights with advanced characterization techniques (e.g., in-situ TEM, deep-level transient spectroscopy) to unlock the full potential of GaN-based power electronics.

 

Toward a p-GaN gate HEMTs Future

This work demonstrates that p-GaN gate HEMTs exhibit recoverable VTH instability under high drain stress, with performance metrics surpassing traditional silicon-based devices. The proposed integration strategies and mechanistic understanding provide a clear pathway for deploying GaN technology in next-generation power systems, aligning with global sustainability goals through improved energy efficiency and reduced material waste.