OPTICAL-PERFORMANCE OF AMORPHOUS HYDROGENATED CARBON LAYERS - RANGE OF OPTICAL-CONSTANTS ACHIEVABLE

The optical properties of differently deposited amorphous carbon layer s have been investigated by spectrophotometric means from the middle i nfrared up to the visible spectral region. The optical constants of th e layers could be calculated by a numerical procedure that combines fe atures of single-wavelength methods and multiwavelength methods. Depen ding on the deposition technique applied, the optical constants of the layers have been found to vary over a wide range. Thus, refractive in dex values could be established between 1.6 and 2.9, while IR-absorpti on coefficients vary between 20/cm and 40,000/cm. The optical performa nce of the layers is thus nonuniform and may be influenced by the sele ction of suitable deposition parameters. Due to the potentially wide r ange of optical constants of amorphous carbon, various possibilities e xist for the application as an optical thin film material. Application s such as selective absorber coatings for solar physical purposes are discussed as well as mechanically and chemically resistant antireflect ion coatings on high-refractive index semiconducting materials (silico n, germanium).