Identification of two-dimensional layered dielectrics from first principles

Developments in the field of two-dimensional van der Waals materials offer big promise for device applications. This study reports a first-principle investigation on the dielectric properties of 32 exfoliable two-dimensional layered dieletrics for assessing the prospects of these materials in devices. To realize effective van der Waals (vdW) transistors, vdW dielectrics are needed in addition to vdW channel materials. We study the dielectric properties of 32 exfoliable vdW materials using first principles methods. We calculate the static and optical dielectric constants and discover a large out-of-plane permittivity in GeClF, PbClF, LaOBr, and LaOCl, while the in-plane permittivity is high in BiOCl, PbClF, and TlF. To assess their potential as gate dielectrics, we calculate the band gap and electron affinity, and estimate the leakage current through the candidate dielectrics. We discover six monolayer dielectrics that promise to outperform bulk HfO2: HoOI, LaOBr, LaOCl, LaOI, SrI2, and YOBr with low leakage current and low equivalent oxide thickness. Of these, LaOBr and LaOCl are the most promising and our findings motivate the growth and exfoliation of rare-earth oxyhalides for their use as vdW dielectrics.

Automated summary

This study evaluates the dielectric properties of 32 exfoliable van der Waals (vdW) materials through first principles methods. Among them, LaOBr and LaOCl show the most promising potential as gate dielectrics, motivating further research and application of rare-earth oxyhalides in device technology.