Shake up satellites and fluorescence property of carbon nitride and hydrogenated carbon nitride: Annealing effect Abhijit Majumdar a, ⁎, Sadhan Chandra Das b , T. Shripathi b , Joachim Heinicke c , Rainer Hippler a a Institute of Physics, Ernst-Moritz-Arndt-University Greifswald, Felix-Hausdorff-Str. 6, 17489 Greifswald, Germany b UGC-DAE Consortium for Scientific Research, Indore 452017, MP, India c Institute for Biochemistry, Ernst-Moritz-Arndt-University Greifswald, Felix-Hausdorff-Str. 4, 17489 Greifswald, Germany abstract article info Article history: Received 14 August 2012 Accepted 8 November 2012 Available online 15 November 2012 Keywords: Hydrogenated carbon nitride carbon nitride Shake up satellites fluorescence 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 °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 promis- ing G and D band is observed only in a-CNx film. A drastic phase transition is observed at/above 300 °C in Fourier transform infrared spectroscopy (FTIR) for a-HCNx film whereas the changes in a-CNx film are less dramatic. At 500 °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. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Amorphous carbon nitride (a-CN x ) and hydrogenated carbon nitride films are expected to be applicable widely as, for example, super hard coating material with low friction coefficient [1–3], low band gap pro- tective material on hard disks and read heads [4,5], photoluminescence layers [6], carbon nitride nano-tubes [7,8], biosensor [9] and anti- biomaterials [10,11], or ultra low dielectric constant material [12]. a-HCNx film properties are more unknown to us due to lack of refer- ence whereas a-C, a-CH, a-CNx, and diamond like carbon (DLC) films have been extensively studied by several authors. In particular, X-ray photoelectron spectroscopy (XPS) [1–7,15–29] and vibration- al spectroscopy (Raman and FTIR) [17,18,20–24,29] measurements have been the most common techniques used to investigate this subject. However, interpretation of these data varies widely in the literature, since the varieties of different bonding configurations are mostly close in energy to each other. And one can face the com- plication by interpreting the spectra with a multitude of overlapping peaks, which makes deconvolution of the curve problematic. a-CNx film is expected to be a hard film but a-HCNx film is amorphous and inhomogeneous due to the presence of hydrogen in the film [24]. Major significant obstacles to the synthesis of crystalline β-C 3 N 4 are 1) the existence of N\H and C\H x bonds which are formed in most of the deposition systems and 2) the incorporation of the nitrogen in the carbon layer to reach a N/C ratio of ≈1.33. Hypothetical pre- diction regarding the mechanical property superiority of β-C 3 N 4 solids to those of diamond [30] has attracted a great interest towards carbon\nitrogen materials but still there is no conclusive evidence about the possibility of synthesizing such super hard crystalline solids. The graphitic carbon nitride polymers also possess a stacked two-dimensional structure, which could be regarded as N-substituted graphite in a regular manner as mentioned by Zhang et al. [31]. The structure and chemical bonding states of a-CN x films are fre- quently analyzed by FTIR, XPS, and solid state NMR spectroscopy. The FTIR spectra showed overlapped bands in the NH and OH regions despite that hydrogen was not a precursor during film deposition. Moreover, the temperature effect and thermal stability of those films were a big concern. These factors may be due to the complexity of the amorphous structure. The chemical bonding states have been analyzed based on the peak deconvolution of the C-1s and N-1s spec- tra [14,29–34], and there have been several differing arguments re- garding the deconvolution of these spectra, especially that of N-1s. We observed in our previous study [29] that the C-1s peak (maximum at N/C=0.76) is shifted largely towards higher binding energy (from 284.94 eV to 287.4 eV) with increased nitrogen concentration in the deposited CN x film. The, solid state NMR results in our previous study [25] were not evident in the presence of the aromatic compounds but exhibited 1 H and 13 C signals strongly broadened due to homo- and heteronuclear dipolar couplings whereas in other reports it had been Surface Science 609 (2013) 53–61 ⁎ Corresponding author. Tel.: +49 3834864784; fax: +49 3834864701. E-mail addresses: majumdar@physik.uni-greifswald.de, majuabhijit@gmail.com (A. Majumdar). 0039-6028/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.susc.2012.11.003 Contents lists available at SciVerse ScienceDirect Surface Science journal homepage: www.elsevier.com/locate/susc