Shake up satellites and fluorescence property of carbon nitride and hydrogenated carbon nitride: Annealing effect

We report the structural difference of amorphous carbon nitride (a-CNx) and hydrogenated carbon nitride (a-HCNx) films as a function of annealing temperature. The spectroscopic analysis suggests that the presence of oxide layer is not the prime cause but the surface chemical property is equally responsible for the shake up satellite peak in X-ray photoelectron spectrum (XPS). XPS spectra of a-HCNx films show a strong shake up peak whereas it is absent in XPS of a-CNx films. XPS core level peak of a-HCNx shows a higher chemical shift compared to a-CNx. Shake up peak disappeared at 500 degrees C and the core peak intensity is increased. Raman spectra display a strong fluorescence effect of a-HCNx and a-CNx at room temperature but a promising G and D band is observed only in a-CNx film. A drastic phase transition is observed at/above 300 degrees C in Fourier transform infrared spectroscopy (FTIR) for a-HCNx film whereas the changes in a-CNx film are less dramatic. At 500 degrees C the hypsochromic shift of the sp(1)-band energy in a-HCNx film is 7 times higher compared to the same a-CNx film. (C) 2012 Elsevier B.V. All rights reserved.