1. Components of atom:

Electrons, protons, neutrons

1. What is a valence electron?

Electrons on the last, most outer shell. They are are not strongly connected with the nucleus

1. What is a free electron?

Electron released from the outer shell.

1. Name the two semiconductor materials

Silicon, Germanium

1. What is a covalent bond?

A covalent bond is the chemical bond that involves the sharing of pairs of electrons between atoms

1. Within which energy band do free electrons exist?

In valence band

1. How are holes created in a intrinsic semiconductor?

By leaving electrons from their orbit.

1. Define recombination.

Inverse process. Recombination is processes by which mobile charge carriers (electrons and electron holes) are created and eliminated.

1. Why is current more easily established in a semiconductor than in an insulator?

Semiconductors will pass electricity through with some restriction. Insulator will not pass electricity

1. How is an n-type semiconductor formed?

An N - type semiconductor is formed when a small amount of pentavalent impurity is added to a pure Germenium or Silicon crystal. The addition of pentavalent impurity produces a large no. of free electrons in the host crystal.

1. How is a p-type semiconductor formed?

A P - type semiconductor is formed when a small amount of trivalent impurity is added to pure Germenium or silicon atom crystal. The addition of trivalent impurity produces a large no. of holes to the host crystals.

1. What are majority carriers in the n-type semiconductor

In n-type semiconductors the majority carriers are electrons

1. What are minority carriers in the p-type semiconductor?

in p-type semiconductors they are positively charged holes Compare minority carrier

1. What is the position of the Fermi level in the n-type semiconductor?

Between valence band and energy gap

1. What is a p-n junction?

a region of a homogeneous semiconductor, where two neighbouring regions are doped with different types of dopes, i.e. one half is n-type and the other half is p-type.

1. What is a depletion layer?

a region at the interface between dissimilar zones of conductivity in a semiconductor, in which there are few charge carriers

1. The barrier potential is greater for silicon or for germanium?

For silicon

1. What is the barrier potential for silicon?

0,7 V

1. Name the two bias conditions.

Forward, reverse

1. Which bias condition produces majority carriers current?

Forward bias

1. Which bias condition produces a widening of the depletion layer?

Reverse bias

1. Name the two types of reverse-bias breakdowns.

Avalanche breakdown, Zener breakdown

1. Is Zener breakdown a reversible phenomenon or not?

Yes, it is.

1. Which type of breakdown requires a greater voltage?

Avalanche breakdown

1. Sketch the I-V characteristic of the forward-biased p-n junction