Identification of two-dimensional layered dielectrics from first principles

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Chemistry

Background:

• Effective van der Waals (vdW) transistors require vdW channel materials and vdW dielectrics.
• The development of novel vdW dielectrics is essential for advancing transistor technology.

Purpose of the Study:

• To investigate the dielectric properties of 32 exfoliable vdW materials.
• To identify promising vdW dielectric candidates for transistor applications.
• To compare the performance of potential vdW dielectrics with bulk HfO2.

Main Methods:

• Utilizing first-principles computational methods to study dielectric properties.
• Calculating static and optical dielectric constants.
• Assessing band gap, electron affinity, and estimating leakage current for potential dielectrics.

Main Results:

• Identified GeClF, PbClF, LaOBr, and LaOCl with large out-of-plane permittivity.
• Found BiOCl, PbClF, and TlF exhibit high in-plane permittivity.
• Discovered six monolayer dielectrics (HoOI, LaOBr, LaOCl, LaOI, SrI2, YOBr) with potential to outperform bulk HfO2.
• LaOBr and LaOCl show particular promise due to low leakage current and equivalent oxide thickness.

Conclusions:

• LaOBr and LaOCl are highly promising vdW dielectric materials.
• Rare-earth oxyhalides warrant further investigation for vdW dielectric applications.
• The findings provide a foundation for the development of next-generation vdW transistors.