Explanation: A heavily doped n+ region is sandwiched between the n-type epitaxial collector and p-type substrate. This buried n+ region provide a low resistivity current path from active collector region (n-type layer) to the collector contact (n+ contact layer). In effect, the n+ layer shunt n-layer of collector region with respect to flow of current, thus effectively reduces the collector resistance. 7. At what potential, the substrate of a vertical pnp transistor should be kept to attain good isolation?
A. Same potential
B. Positive potential
C. Different potential
D. Negative potential
Answer:A
Explanation: A heavily doped n+ region is sandwiched between the n-type epitaxial collector and p-type substrate. This buried n+ region provide a low resistivity current path from active collector region (n-type layer) to the collector contact (n+ contact layer). In effect, the n+ layer shunt n-layer of collector region with respect to flow of current, thus effectively reduces the collector resistance. 7. At what potential, the substrate of a vertical pnp transistor should be kept to attain good isolation?
A. Same potential B. Positive potential C. Different potential D. Negative potential