| 摘要 |
1,057,817. Gallium arsenide diodes. WESTERN ELECTRIC CO. Inc. Oct. 17, 1963 [Oct. 23, 1962; May 13, 1963], No. 41009/63. Heading H1K. A silver layer of from ¢ to 1 mil. thickness is deposited on a limited area of a gallium arsenide wafer, or on a gold layer on the wafer, with a layer of gold applied over the silver layer. In one embodiment (Fig. 1) a slice 20 of lowresistivity N-type gallium arsenide has a thin high resistivity layer 22 epitaxially grown on its surface. Upon the layer 22 are deposited several contacts 24 by evaporation through a metal mask. These consist of gold, 24 and 26 and silver 25. A tin layer is alloyed to the other face of the wafer during this process. After masking the contact regions 24 with wax, etching of the wafer is effected and the slice is cut up ultrasonically into individual wafers, each with a button contact. Housing and encapsulation of the element with a spring contact 29 on the button completes the device. In a further embodiment, however (Fig. 2, not shown), the N- type wafer is provided with a thin P-type region of low conductivity produced by zinc diffusion, a silver button is evaporated on the wafer through a mask, and at a lower temperature a thin gold plating is provided over the silver. After ultrasonic cutting of the wafer into discrete elements, etching of the PN junction is effected to remove part of the P-type region. Finally after thermocompression bonding the lead wire to the silver button the device is encapsulated. |
