Nanometer-Thick Single-Crystal Hexagonal Gd2 O3 on GaN for Advanced Complementary Metal-Oxide-Semiconductor...

Area of Science:

• Materials Science
• Solid State Physics
• Semiconductor Device Physics

Background:

• Gallium Nitride (GaN) is a crucial semiconductor for high-power and high-frequency electronics.
• High-quality gate dielectrics are essential for advanced GaN-based metal-oxide-semiconductor (MOS) devices.
• Exploring novel dielectric materials with superior properties is critical for device performance enhancement.

Purpose of the Study:

• To deposit hexagonal-phase single-crystal Gadolinium Oxide (Gd2 O3) on Gallium Nitride (GaN) using molecular beam epitaxy.
• To characterize the dielectric properties and thermal stability of the hexagonal Gd2 O3/GaN heterostructure.
• To evaluate the potential of this heterostructure for next-generation semiconductor devices.

Main Methods:

• Deposition of hexagonal-phase single-crystal Gd2 O3 on GaN via molecular beam epitaxy.
• Measurement of dielectric properties, including the dielectric constant.
• Characterization of capacitive effective thickness.
• Assessment of thermal stability and interfacial properties through high-temperature annealing.

Main Results:

• The hexagonal Gd2 O3 exhibits a dielectric constant approximately twice that of its cubic form on other substrates (InGaAs, Si).
• A remarkably low capacitive effective thickness of 0.5 nm was achieved for hexagonal Gd2 O3 on GaN.
• The Gd2 O3/GaN heterostructure demonstrates excellent thermodynamic stability at elevated temperatures.
• Low interfacial densities of states were observed after high-temperature annealing, indicating a high-quality interface.

Conclusions:

• Hexagonal Gd2 O3 is a promising high-k dielectric material for GaN-based MOS devices.
• The superior dielectric properties and thermal stability make it suitable for demanding applications.
• The achieved low effective thickness is a significant advancement for scaling down GaN devices.