Temperature-Independent Current Dispersion in 0.15 μm AlGaN/GaN HEMTs for 5G Applications

Area of Science:

• Materials Science
• Electrical Engineering
• Semiconductor Physics

Background:

• AlGaN/GaN HEMTs are crucial for 5G RF power amplifiers due to high performance.
• Current collapse in these devices, caused by trapping effects, limits output power.
• Understanding trap dynamics is essential for mitigating performance degradation.

Purpose of the Study:

• Investigate trap dynamic response in 0.15 μm GaN HEMTs.
• Identify the origins of current collapse in AlGaN/GaN HEMTs.
• Correlate trap behavior with device performance under RF power amplification conditions.

Main Methods:

• Pulsed I-V characterization to assess current collapse and gate-lag.
• Drain Current Transients (DCTs) to analyze trap dynamics.
• Two-dimensional device simulations to model observed phenomena.

Main Results:

• Significant current collapse observed when pulsing both gate and drain voltages.
• A thermally activated Arrhenius process (E_A ≈ 0.55 eV) linked to Fe doping-induced deep traps.
• A temperature-independent process (1-2 s time constants) attributed to passivation/AlGaN interface states.

Conclusions:

• Iron doping in the buffer layer is a primary source of deep traps causing current collapse.
• Interface states between passivation and AlGaN contribute to a separate, temperature-independent trapping mechanism.
• Findings provide critical insights for designing robust AlGaN/GaN HEMTs for 5G applications.