ELECTRONIC-STRUCTURE AND CHARGE-TRANSFER IN ALPHA-SI3N4 AND BETA-SI3N4 AND AT THE SI(111) SI3N4(001) INTERFACE/

Using a self-consistent linear combination of atomic orbitals method b ased on density-functional theory in a local-density approximation, th e electronic structure in the high-temperature ceramics alpha-Si3N4 an d beta-Si3N4 and at the Si(111)/Si3N4(001) interface have been calcula ted. The resulting charge transfer suggests that the ionic formula can be written as Si3+1.24N4-0.93. For the Si(111)/Si3N4(001) interface, the silicon atoms from the silicon side lose some electrons to the nit rogen atoms of the silicon nitride side forming Si-N bonds at the inte rface. The calculated electronic density of states spectrum of Si 2p c ore levels for this interface is in good agreement with x-ray photoemi ssion spectroscopy experiments.