MSE Ch. 10

A material with an energy band gap of 1 eV will be a semiconductor. This statement is ______. A. True B. False

A

A material with an energy band gap of 5 eV will be an insulator. This statement is ______. A. True B. False

A

A solid characterized by a partially filled valence band is a(n) __________________. A. Conductor B. Semiconductor C. Insulator

A

A solid with Eg=0 is a(n) A. Conductor B. Semiconductor C. Insulator

A

Addition of B (boron) to Si is an example of p-type of conductor. This statement is _____. A. True B. False

A

Addition of P to Si creates n-type of conductor. This statement is ______________. A. True B. False

A

Addition of two P (phosphorus) atoms to 1 million Si (silicon) atoms increases the conductivity by a factor of 5 million. This statement is _____. A. True B. False

A

As temperature increase, the mean time between collisions of electrons in a conductor ______________. A. Reduces B. Increases C. Stays the same

A

As temperature increases, which one of the following statements is INCORRECT? A. The energy of an energy band increases B. The charge mobility decreases C. The drift velocity of electrons decreases D. As the temperature increases, the probability of an electron to occupy higher energy levels is increased.

A

Band gap of a semiconducting material can be determined by measuring its conductivity as a function of temperature. This statement is _______. A. True B. False

A

Both electrons and holes can transport charge. This statement is _____. A. True B. False

A

Carbon in the form of diamond is an electrical insulator. This statement is _______. A. True B. False

A

Energy band gap refers to magnitude of the forbidden energy range between the valence and conduction bands. This statement is ______________. A. True B. False

A

Equation Ne = N0exp(-Eg/2kT ) applies to _______ A. A material with a band gap B. A material with no band gap C. Both A and B D. Neither A or B

A

For a band gap material, number of electrons in the conduction band at a given temperature is given by which of the following equation? (symbols have their usual meaning) A. Ne = N0exp(-Eg/2kT ) B. Ne = N0exp(Eg/2kT ) C. Ne = N0exp(-E2g/2kT )

A

In a solid, which energy band has the highest energy? A. The conduction band. B. The forbidden band. C. The valence band. D. The core band.

A

In most materials, resistivity increases with increase in temperature. This statement is ______. [ρ(T)=ρ0(1+αe∆T), symbols have their usual meaning] A. True B. False This is true in metals and other conductors, but not in semiconductors.

A

In superconducting materials, resistivity approaches zero. This statement is _______. A. True B. False

A

Metal oxides, many ceramics, and most polymers are electrical insulator. This statement is _______. A. True B. False

A

Most common semiconductor materials such Si and Ge have covalent bonds. This statement is ________. A. True B. False

A

Some polymers are electrical conductors. Polyaniline is an example of electrically conducting polymer. This statement is _______. A. True B. False

A

The mean time between collisions of electrons in a conductor will be ______by lattice defects. Thus the mobility of electrons will be _______. A. Decreased, decreased B. Increased, increased C. Decreased, increased D. Increased, decreased

A

Thermoelectric effect can be used to measure the temperature. This statement is _______. A. True B. False

A

Based on the Fermi-Dirac distribution function:f(E)=1/exp[(E―Ef )/kT]+1 , which one of the following statement is correct? A. At E = Ef, f(E) = 1 at any temperature B. At E > Ef, f(E) = 0 at 0 K C. At E < Ef, f(E) = 0 at 0 K D. None of the above

B

Carbon in the form of graphite is an electrical insulator. This statement is _______. A. True B. False

B

A band gap material with a large band gap is likely to be a(n) _________________. A. Conductor B. Semiconductor C. Insulator

C

Based on the following electron distribution in Figures A (two dots) and B (lots of dots and two holes), which one of the following statements is correct? A. The number of charge carriers in Figure A is greater than in Figure B B. The number of charge carriers in Figure A is less than in Figure B C. The number of charge carriers in Figure A is same as in Figure B D. None of the above

C

Based on the following energy band diagrams, which one of the following statements is INCORRECT? A has no band gap, B has a small band gap and C has a large band gap. A. Diagram a represents conductor B. Diagram b represents semiconductor C. Diagram c represents semiconductor D. Diagram c represents insulator

C

The critical energy gap to distinguish between a semiconductor and an insulator is approximately _________________. A. 1.0 eV B. 0.1 eV C. 2.5 eV D. 0.25 eV

C

The number of mobile electrons per atom for aluminum (Z = 13) is ______________. A. 1 B. 2 C. 3 D. 4

C

Which material is NOT a band gap material? A. Silicon B. Diamond C. Copper D. Aluminum doped silicon

C

Which of the following is the correct unit of electrical conductivity? A. Ampere B. Ohms per meter C. Siemens per meter D. None of the above

C

Carbon in the form of carbon nanotube is ________. A. Conductor B. Semiconductor C. Insulator D. Conductor or semiconductor

D

Which of the following has the highest electrical conductivity? A. Polyethylene B. Window glass C. P (phosphorus) doped Si D. Silver

D

Which one of the following equation is the correct equation of the conductivity of a semiconductor as a function of temperature? A. σ = σ0 exp(-Eg/kT ) B. σ = σ0 exp(Eg/kT ) C. σ = σ0 exp(Eg/kT )^2 D. None of the above

D

Which one of the following solids has the highest electrical conductivity? A. Aluminum B. Copper C. Gold D. Silver

D

For electrical conduction, which of the following is correct? (symbols have their usual meaning) A. V = IR B. ρ = (A/L)R C.σ=1/ρ D.σ=Nqμ E. All of the above

E