The miniaturization of transistors is reaching the physical limits of traditional materials, which do not function reliably below a certain thickness. Insulators with a high dielectric constant (κ, >12) and a wide bandgap (>5 eV) are needed to enable smaller transistors, enhancing gate controllability while minimizing unwanted electrical conduction. Now, Yuzheng Guo, Jun He and collaborators, writing in Nature Materials, report the synthesis of single crystals of ultrathin gadolinium pentoxide (Gd2O5) that combine a high dielectric constant of 25.5 and a wide bandgap of almost 7 eV.

In this work, the researchers used particle swarm optimization algorithms to identify the most stable crystal structures of gadolinium oxides of different stoichiometries and then ab initio molecular dynamics simulations to explore the possible stable structures of the resulting candidates. The band structure and density of states calculated by density functional theory for the two most promising structures revealed Gd2O5 as the best candidate for combining a wide bandgap and a high dielectric constant.