AlGaN HEMT Structures Grown on Miscut Si(111) Wafers

Area of Science:

• Materials Science
• Semiconductor Physics
• Device Engineering

Background:

• Aluminum Gallium Nitride/Gallium Nitride (AlGaN/GaN) high-electron-mobility transistors (HEMTs) are crucial for high-power and high-frequency applications.
• Substrate properties, particularly miscut orientation, can influence epitaxial growth and device performance.
• Understanding these influences is vital for optimizing HEMT fabrication.

Purpose of the Study:

• To investigate the effect of substrate miscut on AlGaN/GaN HEMT structures.
• To determine the optimal miscut angle for enhanced device properties.
• To identify the primary factors affecting 2D electron gas mobility.

Main Methods:

• Epitaxial growth of AlGaN/GaN HEMTs on miscut Si(111) wafers using metalorganic vapor phase epitaxy (MOVPE).
• Analysis of strain evolution, surface morphology, and 2D electron gas mobility.
• Numerical analysis to correlate interface properties with electron mobility.

Main Results:

• Wafer misorientation affects strain evolution and surface morphology during growth.
• A weak optimum in 2D electron gas mobility was observed at a 0.5° miscut angle.
• Numerical analysis identified interface roughness as a major factor influencing electron mobility variations.

Conclusions:

• Substrate miscut is a critical parameter influencing AlGaN/GaN HEMT properties.
• Optimizing substrate miscut can enhance electron mobility in HEMTs.
• Interface roughness plays a significant role in determining electron mobility, guiding future material optimization efforts.