J. Stober et al., INITIAL-STAGES OF THE THERMAL NITRIDATION OF THE SI(100) SURFACE WITHNH3 AND NO - A SURFACE SENSITIVE STUDY OF SI 2P CORE-LEVEL SHIFTS, Surface science, 321(1-2), 1994, pp. 111-126
During thermal nitridation of the Si(100) surface, nitride regions gro
w laterally on the surface. Already at small coverages they have nearl
y the thickness which is found for the closed him. This thickness depe
nds on the annealing temperature and is 10 Angstrom for 800 K and 15 A
ngstrom for 1200 K. The coordination of the silicon atoms with nitroge
n atoms is determined by the heating temperature. At 800 K only a smal
l fraction of the silicon atoms in the nitride is bound to four nitrog
en atoms, whereas for 1200 K the majority of the silicon atoms is foun
d in this environment, which is characteristic for stoichiometric sili
con nitride. For 1200 K, growth mode, thickness, and chemical composit
ion are independent of the nitrogen containing gases. For the stoichio
metric closed nitride film we measured the edges of the band gap and t
he position of the Fermi level therein. Defect-induced unoccupied stat
es could be detected within the band gap.