| 摘要 |
856,430. Transistors. MULLARD Ltd. Dec. 13, 1956, No. 38094/56. Class 37 The source and drain electrodes in a field effect transistor are spaced less than 10 mils apart. Fig. 3 shows a source electrode 2 and drain electrode 3 contacting an N-type region of semi-conductor crystal 1, with P-type region 8 in contact with gate electrode 10; the distance ' a' between electrodes 2 and 3 is about 5 mils. In an alternative embodiment (Fig. 4) a gap 12 is cut into the N-type region between electrodes 2 and 3 and part of the N-type layer is removed by etching. Fig. 8 shows a central source electrode 2 surrounded by an annular drain electrode 3; in this example the N-type region was provided by diffusion of impurity into a P-type wafer so that the upper surface of the semi-conductor is of low resistivity material whereby the drain effectively extends to the edge of circular groove 12 lying between electrodes 2 and 3. Electrodes 2 and 3 may be comb or lenticular shaped to provide a long gap between these electrodes. The semi-conductor material may consist of germanium or silicon and an N-type layer may be provided by subjecting the wafer to an atmosphere of antimony trichloride and. hydrogen. The wafer may be etched in hydrogen peroxide, and dip 12 (Fig. 8) may be produced by " depletion layer etching " in sodium hydroxide. Contact 3 may consist of electro-plated nickel, and contact 2 of tinantimony soldered copper. |
