The semi-empirical tight-binding model for carbon allotropes “between diamond and graphite”

Abstract

The new carbon allotropes “between diamond and graphite” have come under intensive examination during the last decade due to their numerous technical applications. The modification of energy gap in thin films of these allotropes was studied experimentally using optical methods. The proposed simple model of carbon clusters with variable lengths of chemical bonds allows us to imitate the transfer from diamond and diamond-like to graphite-like structures, as well as the corresponding modification of hybridization sp3/sp2 for diamond-like and spz for graphite-like phases. This enables us to estimate various allotropes parameters, like the gap Eg, energies of valence Ev, and conduction Ec band edges, and the value of electronic affinity, i.e., optical work function X, which are all of practical importance. The obtained estimations correspond to the experimental data.