Photoelectron spectroscopy study of amorphous carbon thin films as a function of annealing temperature

Abstract

Since amorphous carbon thin films have interesting properties such as high hardness, a low friction coefficient, and chemical inertness, they have attracted a great deal of attention for a wide range of applications. Owing to their properties, amorphous carbon films are mainly used in industrial products such as coatings for the magnetic media of hard disk drives, machine parts for molds, cutting tools and so on. As amorphous carbon films formed by various vapor phase methods include hydrogen atoms, it was pointed out that the thermal stability was not good due to the hydrogen desorption [1]. In this study, the electronic structure in amorphous carbon thin films as a function of annealing temperature was investigated by photoelectron spectroscopy.

Amorphous carbon films were produced by the RF plasma method [2]. Photoelectron measurements were carried out at the BL 7B of NewSUBARU synchrotron radiation facility, University of Hyogo.

Before annealing, a broader peak at 285 eV was observed in the photoelectron spectroscopy spectrum of the C 1s core level as shown in Fig. 1. The photoelectron spectra of the C 1s core level became narrower with increasing annealing temperature. This indicates that the coordination of C atoms in amorphous carbon thin films was changed. By using the curve fitting analysis of the C 1s photoelectron spectra, the coordination of C atoms in amorphous carbon thin films was evaluated as a function of annealing temperature. In addition, the photoelectron spectra of the valence band as a function of annealing temperature were also measured. In the presentation, the electronic structure of amorphous carbon thin films as a function of annealing temperature is discussed.

References

[1] D. R. Tallant, J. E. Parmeter, M. P. Siegal, and R. L. Simpson, Diam. Relat. Mater. 4, 191 (1995).

[2] Y. Haruyama et. al., Jpn. J. Appl. Phys. 60, 125504 (2021).