| 摘要 |
The slightly doped n- silicon substrate (12) has two islands of doped p+ material (14,13) on its surface with a thin layer of p- material (11) in between. The region is highly resistive, being diffused with a dopant of between 0.5 and 4*10<1>2 atoms/sq cm . There is an outer ring of n+ material (17) surrounding the two islands.The voltage connection to one of the islands (B) and the ring (C) are joined so that if the voltage on B and C are slightly greater than that on the second island (A) limiting occurs via the intermediate high resistance zone, with breakdown prevented by the zone between the connector B and C.
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