First-principles determination of potential barriers for field emissions from atomic-scale structures

Abstract

We investigate the self-consistent one-electron potentials and electrostatic potentials of atomic-scale structures in external electric fields by first-principles electronic theory. The tunneling probability of an electron through the potential of Si/Si(100) is found to be larger than those of bare Si(100) and C/Si(100). This is consistent with a large enhancement of the local field around a silicon adatom on the Si(100) surface compared with those near a carbon adatom and on the bare Si(100) surface. We found that the enhancements of the local field at both ends of carbon chains are conspicuous and that the potential barrier for tunneling of C 6 is lower than that of C 5. The result is interpreted in terms of the difference in the electronic states of C 5 (semiconducting) and C 6 (metallic). The present study contributes to the understanding of the microscopic mechanism of electron tunneling for field emissions from atomic-scale structures.