| 摘要 |
1,060,755. Semi-conductor devices. INTERNATIONAL BUSINESS MACHINES CORPORATION. May 27; 1964 [June 28, 1963], No. 21924/64. Heading H1K. A process for increasing the peak current of a tunnel diode comprises passing a current in the forward direction through the diode while monitoring its current-voltage characteristic and increasing the forward current until an initial increase in the peak current is observed. As shown, Fig. 4, a tunnel diode 4 is produced by alloying a dot 3 comprising an alloy of indium, copper, selenium, tellurium and sulphur to the surface of a wafer 2 of gallium arsenide doped with zinc. The device, is chemically etched to reduce the junction to the desired diameter and is then connected in the circuit shown. A forward current supplied by source 13 is switched through diode 4 by an electronic switch 9 operating at 100 kc/s. with a 10: 1 duty cycle. During the part of the cycle in which source 13 is disconnected a curve tracer 10a is connected to diode 4 and the currentvoltage characteristic displayed on a CRO 12. The doping levels are chosen so that initially the diode does not exhibit a negative resistance characteristic. The forward current supplied to the device is slowly increased until a peak appears in the characteristic displayed and is then held constant. The value of the peak current continues to increase and the process is terminated when the peak current reaches a value about 2% lower than its maximum value. In use the peak current of the diode slowly increases to its maximum value and then decreases, the end of the useful life being when the peak current is reduced to a value about 2 % lower than the maximum value. The desired value of peak current of the diode may be produced by an electrolytic etching process monitored using a curve tracer as before. In a second embodiment, Fig. 11, a tunnel diode is manufactured by pyrolytically depositing a layer 21 of silicon dioxide on the surface of a wafer 2 of gallium arsenide. The surface is masked by placing the end of a rod in contact with the oxide layer and applying a layer 22 of resist material. The wafer is chemically etched to dissolve the rod and the oxide layer beneath it to form a small window. Alternatively the window can be etched in the oxide layer using a photo-resist method. A dot 3 of donor material is placed over the window and alloyed to the wafer. The device is then electrically treated as previously described, the etching steps being omitted.
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