Clathrates as effective p-type and n-type tetrahedral carbon semiconductors

Based on ab initio calculations, we predict that a carbon clathrate compound (hexagonal C-40) is suitable to be n doped by Li insertion and p doped by substitutional boron. This material represents an example of n- and p-type tetrahedral carbon semiconductor, alternative to the n-doped diamondlike films whose realization is still in progress. Although this compound has not been synthesized so far, its study can also provide insights into the properties of nanostructured carbon thin films, grown by supersonic cluster beam deposition techniques that display local morphologies similar to the channels and fullereniclike cages present in the system here investigated.