Semiconductors

Question 1

At what temperature do atoms stop vibrating?

Answer 1

Absolute Zero

Question 2

Describe the bands in an insulator

Answer 2

Full valence band, empty conduction band and a band gap

Question 3

Describe the bands in a conductor

Answer 3

Full valence band, partly full conduction band and no band gap

Question 4

Describe the bands in a semiconductor

Answer 4

Full valence band, empty conduction band and tiny band gap

Question 5

What allows electrons to move in a semiconductor?

Answer 5

A voltage applied across it allows the electrons to move

Question 6

Name some semiconductors

Answer 6

Silicon, germanium and selenium

Question 7

What’s the difference between intrinsic and extrinsic semiconductors?

Answer 7

Extrinsic semiconductors have impurities added to them

Question 8

What charge does an n-type semiconductor have?

Answer 8

Neutral

Question 9

What charge does an p-type semiconductor have?

Answer 9

Neutral

Question 10

What’s another name for ‘adding impurities’?

Answer 10

Doping

Question 11

What type of hole does an p-type semiconductor have?

Answer 11

A Positive hole

Question 12

What is the flow in an n-type caused by?

Answer 12

Negative electrons

Question 13

What happens when you stick a p-type and n-type together?

Answer 13

You create a p-n junction

Question 14

Describe a p-n junction

Answer 14

A negative p-type side and a positive n-type with a drift current from negative to positive

Question 15

What’s the minimum voltage for a Forward biased diode (semiconductor) to work

Answer 15

0.7V in the opposite direction

Question 16

What happens when electrons recombibe i in a diode?

Answer 16

They give out a photon

Question 17

What happens when a high energy electron is absorbed?

Answer 17

An electron-hole pair is produced

Question 18

Describe a photodiode

Answer 18

A p-type anode and an n-type cathode

Question 19

Give a use of a reverse photodiode

Answer 19

A light sensor

Question 20

What type of bias does a p-n junction have when the current flows from n-type to p-type?

Answer 20

Forward biased

Question 21

How does a solar cell work?

Answer 21

A photon hits a p-n junction and splits to a p-type and n-type, creating a potential difference

Question 22

Which bias does an LED have?

Answer 22

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