FABRICATION OF SEMICONDUCTOR DEVICES BY MOLECULAR BEAM TECHNIQUES

摘要

1526416 Semiconductor devices WESTERN ELECTRIC CO Inc 27 Aug 1975 [28 Aug 1974] 35290/75 Heading H1K A semiconductor device is made by forming an amorphous layer 102 on a part of a surface of a Group III-V compound substrate 100, heating the substrate 100 to between 450-675‹ C., and directing at the surface of the substrate 100, in an evacuated chamber, at least one molecular beam comprising at least one Group V element and at least one Group III element to grow a monocrystalline layer 108 on the substrate 100 and a polycrystalline layer 106 on the amorphous layer 102. The amorphous layer 102 may be silicon dioxide, silicon nitride or a native oxide, or it may be formed by grit blasting or ion bombarding the surface. The compound may be Cr-doped GaAs or GaP and the molecular beams may contain Ga, As, Sn, Si, Ge, Mg, Be, Al or F, there being an excess of a Group V element at the surface. A low capacitance Schottky barrier mixer diode is formed by continuing the crystal growth to form a more weakly doped monocrystalline layer 110 on the layer 108 by lowering the dopant concentration in the molecular beams containing Ga and As while continuing the deposition. A U-shaped ohmic contact 112 is formed to the N+ layer 108 through the N layer 110 and the device is then covered with a silicon dioxide layer 116 through which a Schottky contact to the layer 110 is made via a finger 114.1 of a contact 114. The polycrystalline layer 106 has sufficient resistance to isolate the device formed in the monocrystalline layers 108, 110. A use of the device with a thin film microwave downconverter circuit is described. Alternatively, a Schottky barrier IMPATT diode may be made.