| 摘要 |
1,028,767. Semi-conductor devices. WESTINGHOUSE BRAKE & SIGNAL CO. Ltd. Sept. 16, 1963 [Oct. 31, 1962; March 22, 1963; April 23, 1963; July 31, 1963], Nos. 41189/62, 11420/63, 15945/63 and 30342/63. Heading H1K. A semi-conductor device with reduced field at the periphery of a PN junction comprises a semi-conductor slice with a PN junction having a mid-portion near one surface and a second portion near the other surface, the depletion layer adjacent the junction extending further at the surface region than it does at the midportion of the junction. Fig. 3 of Specification 1,028,767 shows junction element comprising a high resistivity N-type silicon crystal with a peripheral P-type region 4 produced by diffusing gallium into the surface of a crystal and then cutting it into slices. The crystal is soldered to molybdenum disc 6 by means of an aluminium-silicon alloy resulting in the production of P-layer 10 and tungsten contact 9 is soldered to the N-region of the crystal by means of gold alloy 8. Fig. 7 of Specification 1,028,767 shows a gate controlled PNPN device in which an N-type silicon crystal is subjected to diffusion of gallium to produce a surface P-type layer 36, part of the material then being removed to expose the N-type surface at 34 while leaving a central portion 40 containing PN junction 42. A further N-type region 46 is produced to form another PN junction, ohmic electrodes 48 and 45 being provided to N-type region 46 and P-type region 41. The crystal is soldered to base contact 31. Removal of the material to expose surface 34 may be by etching or grinding and jet etching may be used to undercut region 41 and so decrease the electric field at the surface adjacent the PN junction by increasing the surface length of the depletion zone. Figs. 1 and 2 of Specification 1,028,767 show alternative arrangements in which the P-type region extends along the opposite surface (5a in Fig. 1) or possesses a thickened portion, 5b in Fig. 2. These configurations are said to extend the surface length b of the depletion zone at the region adjacent the exposed end 7 of the junction, compared with the width a of the depletion layer in the central portion. |
