High-k perovskite gate oxide for modulation beyond 10¹⁴ cm^-2

Area of Science:

• Materials Science
• Solid State Physics
• Semiconductor Device Physics

Background:

• Scaling down semiconductor devices necessitates high-k dielectric materials for reduced operating voltage in field-effect transistors (FETs).
• Efficient charge storage in smaller areas requires advanced dielectric properties.
• Perovskite oxides offer potential for next-generation electronic components.

Purpose of the Study:

• To investigate the dielectric properties of epitaxial Barium Hafnium Titanate (BHTO), an alloy of BaHfO3 and BaTiO3.
• To evaluate BHTO's suitability as a gate oxide for modulating two-dimensional (2D) carrier density in FETs.
• To correlate material composition with observed dielectric performance.

Main Methods:

• Epitaxial growth of BaHf0.6Ti0.4O3 (BHTO) thin films.
• Characterization of dielectric properties, including dielectric constant, breakdown field, and leakage current.
• Fabrication and testing of n-type accumulation and depletion mode FETs utilizing BHTO as the gate oxide.

Main Results:

• BHTO exhibits a dielectric constant of 150, a breakdown field of 5.0 MV cm⁻¹, and a leakage current of 10⁻⁴ A cm⁻² at 2 MV cm⁻¹.
• The BHTO gate oxide effectively modulates 2D carrier densities exceeding 10¹⁴ cm⁻².
• Demonstrated successful operation of n-type accumulation and depletion mode FETs.

Conclusions:

• Epitaxial BHTO possesses excellent dielectric properties suitable for advanced FET applications.
• The nanometer-scale stoichiometric modulation of hafnium and titanium in BHTO is attributed to its superior performance.
• BHTO is a promising high-k dielectric material for future low-power, high-density semiconductor devices.