Electron affinity of carbon systems

A tight-binding theory of the electron affinity of semiconductor surfaces is developed, to describe the electron affinity of diamond, non-crystalline carbon, and the effects of various surface terminations such as H and O. The affinity and work function of semiconductors can be calculated from atomic orbital energies for symmetrically bonded atoms, without the need for an explicit surface dipole term. H and O create surface dipoles because of their low bonding symmetries. The low affinity of diamond arises primarily from its wide band gap, despite it being the most electronegative of the group IV elements.