method for the manufacture of a layer eigenleitenden galliumarsenids in a body from n - senior gallium arsenide

摘要

1,142,095. Semi-conductor devices. STANDARD TELEPHONES & CABLES Ltd. 11 Jan., 1968 [13 Jan., 1967], No. 1851/67. Heading H1K. A method of producing an " intrinsic " [semi-insulating] region in an N-type GaAs body comprises diffusing-in oxygen through an oxygen permeable surface layer. The surface layer may be silica and it is stated that oxygen does not convert areas not covered with the oxygen permeable layer. In a first embodiment a PIN diode is pro duced by depositing a layer (3) of silica Fig. 1a (not shown), on the surface of an N-type epitaxial layer 1 on an N + type GaAs substrate 2, and diffusing oxygen through the silica layer to form an intrinsic layer 4, Fig. 1b (not shown). The oxygen is preferably supplied in the form of water vapour. A P+type layer is then produced in the semi-insulating layer 4 by evaporating-on a layer 5 of gold containing zinc at an elevated temperature on to the layer 4, quickly cooling, and evaporating-on a layer 6 of gold at a lower temperature, Fig. 1c (not shown). The electrode is then electroless plated with a layer 7 of nickel followed by a thin layer 8 of gold, Fig. 1d (not shown). The body is cut into mesa diodes, Fig. 1e, which are lightly etched and mounted in individual housings, Fig. 1f (not shown). In a second embodiment, planar type PIN diodes are produced by depositing a layer of silica, removing part of the layer using a photo-resist technique to leave islands, Fig. 2a (not shown), and covering the surface and islands with a second silica layer of equal thickness, Fig. 2b (not shown). Oxygen is then diffused into the body and penetrates to a greater depth in the areas between the islands than in the areas under the islands, Fig. 2c (not shown), so that the breakdown voltage of each diode is determined by the parts of the intrinsic layer under the islands. P + type regions are produced on these thinner parts of the intrinsic layer by the method used in the first embodiment. The body is then cut into individual devices, Fig. 2d (not shown), which are lightly etched and mounted in housings with the electrodes on the P+type regions in contact with copper studs which form heat sinks, Fig. 2e (not shown).