Question

The electrical properties of a transistor in alloy type construction is determined by_________

(a) space between the junctions in the wafer

(b) proportions of N and P type impurities

(c) the pulling rate of crystal

(d) uniformity of the crystal lattice

This question was posed to me in an internship interview.

My enquiry is from Transistor Construction in section Transistor Characteristics of Electronic Devices & Circuits

Answer 1

Correct answer is (a) space between the junctions in the wafer

To elaborate: Large area collector junction helps in collecting most of the holes emitted from the emitter ensuring that the collector current almost equals the emitter current. The spacing between two junctions inside germanium wafer is very small and determines the electrical properties.