New carbon nitride phase coherently grown on Si (111)

Carbon nitride films, deposited on Si(111) substrates at room temperature by XeCl laser ablation of graphite targets in low pressure (1, 5, 10, and 50 Pa) N2 atmosphere at the fluence of 12 J/cm2 (∼0.4 GW/cm2), have been submitted to accurate x-ray diffraction and transmission electron microscopy investigations in order to study the structure of the films. Results showed that the samples are constituted of a continuous amorphous film inside which microcrystals of a new coherently grown CNx phase are dispersed. This new phase has a triclinic crystallographic cell with lattice parameters a=b=0.384 nm, c=0.438±0.007 nm, α=110±1°, β=105±1°, and γ=120°. It coherently grows on the (111) Si plane with the following orientation relationships: (001)CNx ∥(111)Si, [100]CN ∥[1-10)]Si, and [010]CNx ∥[01-1)]Si.