Question

Which of the following is true about grown junction type construction?

(a) N type impurity is added to P type impurity

(b) Boron helps in the prevention  of oxidation

(c) The seed is pulled to a large distance for a correct growth

(d) Slow pulling leads to the formation of P type crystal

This question was posed to me in semester exam.

This is a very interesting question from Transistor Construction in portion Transistor Characteristics of Electronic Devices & Circuits

Answer 1

The correct choice is (d) Slow pulling leads to the formation of P type crystal

To explain I would say: This method is based on the fact that proportion in which N and P type impurities crystallise i.e.., enter the grown crystal depends on the rate of pulling. If the pulling rate is small, a P type crystal is grown. If the pulling rate is fast, an N type crystal is grown.