Layered electrides, as typified by Ca2N, are a new class of quasi-two-dimensional materials with low work functions. Using first-principles calculations, we have shown that a graphene layer deposited on Ca2N is doped to n=5×1014 cm−2 with its Fermi level aligned with the logarithmically divergent van Hove singularity in the graphene π∗ band. For bilayer graphene on Ca2N, the inner graphene layer is doped to the same level, while the doping of the outer graphene layer is much more modest. This finding opens an interesting possibility of using layered electrides for the exploration of van Hove physics. The work function changes nonmonotonically with the number of graphene layers, which we explain in terms of the peculiar electronic structures of the constituent materials and their bonding.
@article{arxiv.1708.01048,
title = {Probing a divergent van Hove singularity of graphene with a Ca$_2$N support: a layered electride as a solid-state dopant},
author = {Takeshi Inoshita and Masaru Tsukada and Susumu Saito and Hideo Hosono},
journal= {arXiv preprint arXiv:1708.01048},
year = {2017}
}