Tutorial 2

Question 1

The periodic table of elements is arranged on the basis of

Answer 1

Atomic number

Question 2

Which of the following statements concerning the semiconductor doping process is true?

Answer 2

Donors donate electrons

Question 3

Another name for a trivalent atom

Answer 3

An acceptor

Question 4

Which of the following statements concerning the semiconductor charge carrier is true?

Answer 4

The conductivity of semiconductors is dominated by their extrinsic carrier concentration.

Question 5

Can the Fermi level be changed via doping

Answer 5

Yes

Question 6

True or false , donors introduce an extra level close to Ec

Answer 6

Tru

Question 7

How do intrinsic semiconductors behave

Answer 7

They have very few charge carriers therefore they behave like insulators

Question 8

Fermi energy level for semi conductor

Answer 8

Ef=(Ec+Ev)/2

Question 9

Fermi level for P type semiconductor

Answer 9

Ef

Question 10

Fermi level for N type semi conductor

Answer 10

Ef>(Ec+Ev)/2

Question 11

What is the overall charge of a P type semiconductor

Answer 11

Neutral

Question 12

Define intrinsic semiconductor

Answer 12

Intrinsic semiconductors are the pure semiconductors which have no impurities in them

Question 13

Define Ev in band theory and describe its band occupancy status at 0 K.

Answer 13

Ev highest possivle valence band energy
The top of the valence band.
Below Ev is completely full (with electrons) at 0K.

Question 14

Define Eg in Band theory

Answer 14

The energy required to free an electron from a covalent bond.
The energy gap between the top of the valence band and the bottom of the conduction band.
Eg = Ec – Ev

Question 15

Define Ef in band theory

Answer 15

A state with 50% chance of being occupied by an electron at a given temperature.

At absolute zero no electrons will have enough energy to rise above the Fermi level.

Question 16

A semiconductor is said to be a ________ type of material

Answer 16

Crystalline

Question 17

An intrinsic semiconductor does not have

Answer 17

an excess of electrons
an excess of holes
a large number of impurities
Feedback

Question 18

Conduction in the conduction band of semiconductors is by the movement of

Answer 18

Electrons

Question 19

Three examples of semiconductors

Answer 19

Gallium arsenide
Germanium
Silicon

Question 20

Holes are the majority carriers in

Answer 20

A p type semiconductor

Question 21

Silicon and germanium contain ——- valence electrons

Answer 21

4

Question 22

True or false, In the quantum model of the atom, an orbital is a discrete energy level where an electron is found.

Answer 22

False

Question 23

Tru or false, A p-type semiconductor has relatively few free electrons

Answer 23

Tru

Question 24

Tru or false Hole flow occurs in the conduction band

Answer 24

False

Question 25

The valence band has lower energy than the conduction band, t or f

Answer 25

Tru