Valence band offset and interface stoichiometry at epitaxial Si3 N4 /Si (111) heterojunctions formed by plasma nitridation

Abstract

Ultrathin β -Si3 N4 (0001) epitaxial films formed by N2 -plasma nitridation of Si(111) substrates have been studied by photoelectron spectroscopy using synchrotron radiation. The valence band offset at the β -Si3 N4 /Si interface was determined by valence-band photoelectron spectra to be 1.8 eV. Furthermore, the Si 2p core-level emissions were analyzed for nitride (Si4+) and subnitride (Si3+ and Si+) components to characterize the interface stoichiometry. In contrast to the interfaces formed by ammonia thermal nitridation and N2 -plasma nitridation at room temperature, the interface formed by N2 -plasma nitridation at high substrate temperature is very close to subnitride free with an abrupt composition transition. © 2009 American Institute of Physics.