Semiconductors

Question 1

What is an insulator? Give examples.

Answer 1

A material that does not conduct electricity.

Plastic, Glass, Wood.

Question 2

What is a semiconductor?

Answer 2

When pure, acts as insulator. Can be made to conduct when an impurity is added, or in response to light, heat, voltage, etc.

Silicon, gallium, germanium.

Question 3

What is the Conduction band?

Answer 3

The band above the valence band, electrons jump into it to from the valence band when they have enough energy.

Question 4

what is the Valence Band?

Answer 4

The band the outermost electrons occupy. Electrons jump from this band to the conduction band when excited.

Question 5

Doping

Answer 5

The addition of an impurity atom to a semiconductor in order to increase its conductivity.

Question 6

P-N Junction (Diode)

Answer 6

The junction formed when a piece of p-type material is grown together with a piece of n-type material.

will only let current flow through in one direction

Question 7

Forward bias

Answer 7

when the negative terminal of the cell is connected to the n-type and the positive terminal of the cell is connected to the p-type.

forward bias reduces the electric field in the p-n junction

Question 8

reverse bias

Answer 8

When the negative terminal of the cell is connected to the p-type and the positive terminal of the cell is connected to the n type.

This increases the electric field in the p-n junction

Question 9

LED

Answer 9

A forward biased p-n junction diode that emits photons due to recombination.

Question 10

Solar cell

Answer 10

A p-n junction that produces a potential difference when photons are absorbed.

Question 11

What is the photovoltaic effect?

Answer 11

The name given to the production of a voltage when a solar cell absorbs incident photons.