Hydrogenated amorphous carbon films (a-C:H) were deposited on glass, silicon and germanium substrates. The films are transparent in the IR and are extremely hard. The a-C:H films were homogeneously deposited at a rate of about 500 A/min in an RF excited discharge from benzene vapour. The characteristic features of this deposition method are discussed. Thickness, short wavelength absorption, refractive index (2 - 10 micrometers) and relative hydrogen content were determined. Variations in short wavelength absorption, IR-refractive index and relative hydrogen content could be correlated with deposition conditions. The refractive index of a-C:H can be tuned to be exactly 2, thus a-C:H is an ideal single layer AR-coating for germanium (n = 4). Laser calorimetric measurements of optical absorption at 10.6 micrometers give an absorption coefficient of 250/cm. The application of a-C:H as single layer AR coating on Ge and as outside layer of a multi-layer coating is demonstrated.

Hydrogenated amorphous carbon films a-C:H were deposited on glass and germanium substrates. The films are transparent in the IR and are extremely hard (Mohs's hardness of about 8). The a-C:H coatings were prepared according to the method of Holland in an RF excited discharge sustained by various hydrocarbon gases.

This book includes a comprehensive presentation of the fundamental physics of optical matter, the definition of material physical properties, the listing and comparison of the physical properties of infrared optical materials, and the theory, design, and survey of infrared optical coatings.