Optical and electrical properties of nitrogen incorporated amorphous carbon films

Abstract

Nitrogen incorporated amorphouscarbon (a- C:N ) films on silicon (111) wafer, quartz, and Ti/C substrates with nitrogen concentration up to 20 at. % are prepared by filtered arc deposition. The nitrogen concentration and area density of the films were measured by Rutherford backscattering. The electrical properties of the films were investigated by Hall electrical measurements. The optical properties of the films were characterized by ultraviolet–visible and infrared reflection spectrometry. Results indicate that the optical band gap and area density of a- C:N films decrease with increasing nitrogen pressure, accompanied with an increase of nitrogen concentration and reflectivity of the films. Furthermore, the influence of nitrogen concentration on the optical band gap of the films is discussed. The dielectric constant, refractive index and absorption coefficient of a- C:N films in infrared region were investigated. The results indicate that the optical constants of a- C:N show considerable variation with wave number and nitrogen content. The variation of optical properties and optical constants of a- C:N films may be due to the development of graphite-like structure with the increasing of nitrogen content in these films.