Formation of a Graphene-Like SiN Layer on the Surface Si(111)

Abstract

00-The kinetics of the formation and thermal decomposition of a two-dimensional SiN-(8 x 8) nitride layer on a Si(111) surface is studied. The SiN-(8 x 8) structure is a metastable intermediate phase formed during the nitridation of silicon before the formation of a stable amorphous Si3N4 phase. Studying the SiN-(8 x 8) structure by scanning tunneling microscopy shows its complex structure: it consists of an adsorption (8/3 x 8/3) phase, with the lateral period 10.2 angstrom, and a honeycomb structure with a 6 angstrom side of a hexagon that is turned 30 degrees with respect the adsorption phase. The band gap of the SiN-(8 x 8) phase is measured and found to be 2.8 eV, which is smaller compared to the band gap of the -Si3N4 crystal phase 5.3 eV. The interplanar spacings in the (AlN3)/(SiN)(2) structure on the Si(111) surface are measured. The spacings are 3.3 and 2.86 angstrom in SiN and AlN, respectively. Such interplanar spacings are indicative of weak van der Waals interaction between the layers. A model of the SiN-(8 x 8) structure as a flat graphene-like layer is suggested. The model is consistent with the diffraction and microscopy data.