A Simulation Optimization Factor of Si(111)-Based AlGaN/GaN Epitaxy for High Frequency and Low-Voltage-Control High...

Area of Science:

• Materials Science
• Semiconductor Physics
• Electrical Engineering

Background:

• High-resistance Si (111)-based AlGaN/GaN heterojunction epitaxy is crucial for high electron mobility transistors (HEMTs).
• Device performance metrics like knee-point voltage (V), saturation current density (I), and cut-off frequency (f) are sensitive to epitaxial layer parameters.
• Optimizing these parameters is essential for developing advanced GaN-based electronic devices.

Purpose of the Study:

• To investigate the impact of barrier layer thickness, Al component, and passivation layer thickness on HEMT performance.
• To propose a novel optimization factor (OPTIM) for designing AlGaN/GaN epitaxial structures.
• To achieve reduced knee-point voltage and improved saturation current density while ensuring high cut-off frequency.

Main Methods:

• Simulation and analysis of AlGaN/GaN heterojunction epitaxy using varying barrier layer thickness, Al composition, and passivation layer thickness.
• Development and application of a novel optimization factor (OPTIM) considering multiple device performance parameters.
• Fabrication and experimental testing of the optimized AlGaN/GaN HEMT structure to validate simulation results.

Main Results:

• An optimized structure with 20 nm barrier layer thickness, 25% Al component, and 6 nm SiN passivation layer was designed.
• Simulated HEMT (0.15 μm gate length) achieved a high saturation current density of 750 mA/mm and a low knee-point voltage of 2.0 V.
• The device demonstrated a cut-off frequency (f) of 110 GHz and a maximum frequency (f_max) of 220 GHz.

Conclusions:

• The proposed OPTIM factor provides an effective design methodology for AlGaN/GaN HEMTs.
• The optimized epitaxial structure enables high-frequency and low-voltage device operation.
• This approach facilitates the development of next-generation GaN-based high-frequency power devices.