| 摘要 |
997,965. Semi-conductor devices. WESTERN ELECTRIC CO. Inc. Sept. 5, 1961 [Sept. 6, 1960], No. 31852/61. Heading H1K. In a tunnel effect device with an improved peak-valley current ratio degenerate P and N- type zones are separated by a thin layer of a material with an energy gap at least 3 electron volts less than that of either the P or the N-type zone. The effective electron mass in the layer material which may be intrinsic or N or P-type should be as small as possible. In addition, to avoid high concentrations of recombination centres at the interfaces between the layer and the zones, the lattice constants and orientation of adjoining layers should match sufficiently to produce not more than one dislocation per 20 atoms at either interface, e.g. lattice constants should match to within 5% and the crystallographic orientations to within 3 degrees. Suitable materials for the thin layer, which is preferably 10-300 Š thick, are indium antimonide in association with P and N zones of cadmium telluride; indium arsenide or mercury selenide with cadmium selenide; and mercury telluride with cadmium telluride. The layer may be produced by vapour depositing the low energy gap material on the end of a block of degenerate P or N-type high-energy gap material, pressing the block against a block of opposite conductivity type and heating to fuse the blocks together. Alternatively the P and N-type blocks are closely spaced in a melt of the layer material which is drawn up between them by capillary attraction. The assembly is then rapidly cooled with the blocks pressed together to squeeze out excess melt to reduce the layer thickness to the desired value.
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