| 摘要 |
1,136,218. Coatings of inorganic compounds or elements. STANDARD TELEPHONES & CABLES Ltd. 14 Dec., 1965, No. 52993/65. Heading C1A. [Also in Divisions C4, C7 and H1] In a method of providing an anti-reflecting coating on an optical surface of a semi-conductor optical device, the surface is coated with a layer comprising an element or an inorganic compound, the energy necessary to promote the required chemical action for the formation of the layer being provided by establishing a plasma adjacent to the surface in an atmosphere which when the layer comprises an element contains the said element as a compound and which when the layer comprises an inorganic compound contains all the elements of said inorganic compound, all the inorganic compound elements being present in the atmosphere as inorganic materials other than said inorganic compound with at least one of these inorganic materials being an inorganic compound. The optical device may be a light emitting device such as a gallium arsenide light emitting diode or a light receiving device such as a photodiode or photo-cell. The term light includes the visible, ultra-violet and infra-red regions of the spectrum. Fig. 1 shows apparatus for providing silicon nitride anti-reflecting coatings on gallium arsenide light emitting diodes 8 on a support 7 in a glass tube 1. A vacuum pump connected to an outlet 3 reduces the system pressure to OÀ2 torr and SiH 4 and NH 3 are supplied through an inlet 2. An R.F. power source with an output frequency of 4 mc./sec. is connected to a metal mesh which surrounds the tube 1 to produce a plasma. Other coatings (c) which may be provided and the starting materials (m) forming the gaseous atmosphere are The coating may comprise a single layer, a multiple layer or a graded layer, e.g. of silica merging into titanium oxide, e.g. produced by progressively changing the constituents of the gaseous atmosphere. Fig. 3 shows an anti-reflecting silicon nitride layer 18 on a gallium arsenide light emitting diode element comprising a body 14 of N-type gallium arsenide having a P-type region 16, a silica layer 15 and an indium electrode 17, the whole being sandwiched between copper plates 9a, 9b. |
