Infra-red transparent optical components

Abstract

A method of coating a substrate in a glow discharge chamber uses a source of hydrocarbon and another element. Butane and germane are used to deposit a coating of Ge.sub.x C.sub.1-x where 0<x<1 onto a germanium substrate. The substrate temperature is maintained above 400.degree. C., typically 530.degree. C., during growth to prevent inclusion of H.sub.2 in the coating. The presence of Ge in the coating allows thick, stain-free, layers to be grown. Alternatively, butane and silane may be used to deposit Si.sub.x C.sub.1-x. Varying the proportions of the hydrocarbon and germane or silane allows a variation in the value of x. A method of growing a combined layer of at least a first and a second material in glow discharge chamber. A target cathode formed on the first material, e.g., Si, Ge, W is arranged in the chamber and spaced from a substrate to be coated. Argon gas and a gas of the second material, e.g., a hydrocarbon, are admitted into the chamber and a glow discharge established. Hydrocarbon ions from the glow discharge plasma strike and deposit on the cathode target. Argon ions sputter off atoms of both C and bulk target material, e.g., Si, Ge, or W, which deposit onto the substrate and gradually build up a combined layer of, e.g., Si.sub.x C.sub.1-x, Ge.sub.x C.sub.1-x, W.sub.x C.sub.1-x wherein 0<x<1. Optical lens components, infra-red transparent, made from these processes are also disclosed.