**Abstract**

A systematic study of kinetics and thermodynamics of Si (111) surface nitridation under ammonia exposure is presented. The appeared silicon nitride (8 × 8) structure is found to be a metastable phase. Experimental evidences of graphenelike nature of the silicon nitride (8 × 8) structure are presented. Interlayer spacings in the (SiN)2(AlN)4 structure on the Si (111) surface are found equal to 3.3 Å in SiN and 2.86 Å in AlN. These interlayer spacings correspond to weak van der Waals interaction between layers. In contrast to the widely accepted model of a surface structure (8 × 8) as monolayer of β-Si3N4 on Si (111) surface, we propose a new graphene-like Si3N4 (g-Si3N3 and/or g-Si3N4) model for the (8 × 8) structure. It is revealed that the deposition of Al atoms on top of a highly ordered (8 × 8) structure results in graphene-like AlN (g-AlN) layers formation. The g-AlN lattice constant of 3.08 Å is found in a good agreement with the *ab initio* calculations. A transformation of the g-AlN to the bulk-like wurtzite AlN is analyzed.

**Keywords:** kinetics and thermodynamics of 2D layers formation, van der Waals interaction, graphene-like silicon nitride, g-AlN, sp3 - and sp2 -hybridization, π-orbitals, RHEED, STM, STS, HRTEM

### **1. Introduction**

After the discovery of graphene, significant effort is spent to create other graphene-like (graphite-like) materials. Among them, much attention was attracted to graphite-like carbon-nitride compounds g-C3N3 and g-C3N4 [1–10]. These materials consist of covalently bound sp2 -hybridized carbon and nitrogen atoms. Interest in them is caused by theoretical predictions of new mechanical, electronic, magnetic, and photocatalytic properties [1–9]. To date, the compound g-C3N4 has been synthesized [10], and it has been demonstrated that the layers of g-C3N4 have a bandgap width in the range of 1.6–2.0 eV, which makes it possible to use the semiconductor layer to create electronics and optoelectronics devices, such as field effect transistors, photodetectors, light-emitting diodes, and lasers. Since silicon is in the same group as carbon in the periodic table, then graphene-like Si-N sheets, where C atoms are replaced by Si atoms, are expected to demonstrate the unusual properties.

Dielectric materials that provide insulation of conductive channels are also necessary for the development of electronic devices. Hexagonal-BN (h-BN), one of the 2D dielectric materials [11, 12], attracts grate attention. However, the fabrication of large area h-BN layers is difficult. AlN is another alternative dielectric material that can be grown epitaxially on large areas. It is also predicted [13] that silicene is stable when encapsulating between two thin graphite-like hexagonal AlN layers. This is especially important, since until now silicene growth has been presented only on metal substrates, which makes it unsuitable for electronic devices. In this chapter, the synthesis and properties of the graphene-like materials and van der Waals layers of silicon nitride (g-SiN) and aluminum nitride (g-AlN) are reported.
