Chapter 10

Question 1

charge carriers

Answer 1

electrons, electron holes, anions, cations

Question 2

which material has the highest conductivity

Answer 2

metals, then semiconductors

Question 3

types of semiconductors

Answer 3

Silicon, Germanium

Question 4

conductivity of ceramics

Answer 4

mostly low, except for a few (Fe3O4 and RuO2)

Question 5

conductivity of polymers

Answer 5

low

Question 6

rank materials from most to least resistive

Answer 6

insulators
semiconductors
metallic
superconductor

Question 7

what happens to the electron distribution in a partially filled band when temperature increases

Answer 7

electrons begin to shift and spread out (representative of metallic behavior)

Question 8

Fermi-Dirac Statistics

Answer 8

occupancy is higher the higher the temperature

Question 9

energy band diagrams for conductors

Answer 9

no gap at all

partially filled valence band at 0 K

Question 10

energy band diagrams for semiconductors

Answer 10

small gap
completely filled valence band at 0 K
Eg <= 2.5

Question 11

energy band diagrams for insulators

Answer 11

large gaps
completely filled valence band at 0 K
Eg > 2.5

Question 12

charge carriers for metals

Answer 12

electrons
N is constant
q is constant
mu ~ (1/T)

Question 13

charge carriers for semiconductors

Answer 13

electrons and holes

N increases with increasing temperature

Question 14

charge carriers for insulators

Answer 14

anions, cations, electrons, and holes
N increases with increasing temperature
q varies according to charge carrier

Question 15

factors that affect conductivity in metals

Answer 15

vacancies, foreign atoms, thermal vibrations

Question 16

influence of alloying in conductivity

Answer 16

alloying decreases conductivity

Question 17

influence of cold working on conductivity

Answer 17

decreases conductivity

Question 18

number of charge carriers in insulators

Answer 18

depends exponentially on temperature

Question 19

carrier transferrence number

Answer 19

t= sigma(carrier)/sigma(total)

Question 20

n-type conductivity

Answer 20

an extra electron from a group V donor atom hovers in the gap along the Ed line
extrinsic

Question 21

p-type conductivity

Answer 21

an electron hole created by an atom with less electrons hovers in the gap along the Ea line
extrinsic

Question 22

Define: E(g) DeltaE, mu(e) mu(h) N

Answer 22

Eg=band gap
DeltaE=impurity energy levels
mu_e=electron mobility
mu_h=hole mobility
N=carrier density

Question 23

Dopants for Silicon

Answer 23

P, Sb, Al, Ga

Question 24

Dopants for Ga As

Answer 24

Se, Cd

Question 25

p-n junction

Answer 25

basis of all microelectronic devices

reverse bias limits amount of current that can flow and forms an insulating barrier at junction

Question 26

concept of superconductivity

Answer 26

At the critical temperature, the vibrational frequency of the electron pairs corresponds to the vibrational frequency of the atomic nuclei. The result of this correlation between vibrational frequencies is a synchronized motion of the electron pairs through the vibrating crystal lattice. Because the motion is synchronized, the time between collisions, and hence the conductivity, increases without limit

Question 27

intrinsic conduction

Answer 27

semiconducting behavior resulting from the band structure of a pure element or compound

Question 28

extrinsic conductions

Answer 28

semiconducting behavior facilitated by the presence of impurities

Question 29

forward bias

Answer 29

when the negative potential is applied to the n-type side of the p-n junction