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Ch 21, set 1 1. The band structure helps us to explain why impurities make the conductivity go __ for metals and __ for semiconductors. a. down; up b. up; down c. up; up d. down; down e. none of the above 2. The conductivity in doped semiconductors is affected by __ and __. a. pressure; temperature...

Ch 21, set 1 1. The band structure helps us to explain why impurities make the conductivity go __ for metals and __ for semiconductors. a. down; up b. up; down c. up; up d. down; down e. none of the above 2. The conductivity in doped semiconductors is affected by __ and __. a. pressure; temperature b. impurities; temperature c. impurities; pressure d. volume; temperature e. none of the above 3. The temperature affects the __ of intrinsic semiconductors. a. bandgap b. atomic nature c. conductivity d. Miller indices e. none of the above 4. Doped semiconductors can be __ or __. a. s-type; p-type b. p-type; n-type c. p-type; o-type d. a-type; b-type e. none of the above 5. Doped semiconductors are used to make __. a. superconductors b. metallic devices c. electronic devices d. ceramic devices e. none of the above 6. Elemental semiconductors are typically group __ materials. a. IA b. IIA c. IIIA d. IVA e. none of the above 7. Examples of elemental semiconductors are __ and __. a. Fe; Ni b. Cu; Al c. Si; GaAs d. Sn; Pb e. Si; Ge 8. Compound semiconductors include __ compounds and __ compounds. a. III-V; II-VI b. I-II; II-III c. I-III; I-IV d. III-V; IV-IV e. none of the above 9. Examples of III-V compound semiconductors include __ and __. a. SiGe; GaAs b. GaAs; InSb c. ZnSe; InSb d. GaAs; ZnTe e. none of the above 10. Examples of II-VI compound semiconductors include __ and __. a. SiGe; GaAs b. ZnSe; InSb c. CdS; ZnTe d. GaAs; ZnTe e. none of the above 11. In compound semiconductors, the wider the __ difference between the constituting elements, the __ the energy bandgap. a. electronegativity; narrower b. electronegativity; wider c. atomic radius; narrower d. atomic radius; wider e. none of the above 12. In an intrinsic semiconductor, the valence band is typically __ and the conduction band is typically __. a. partially filled; partially filled b. completely filled; partially filled c. partially filled; completely filled d. completely filled; completely empty e. none of the above 13. In an intrinsic conductor, __ causes an electron to jump from the __ band to the __ band. a. momentum; conduction; valence b. thermal excitation; valence; conduction c. thermal excitation; conduction; valence d. magnetism; electric; magnetic e. none of the above 14. In an intrinsic conductor, thermal excitation creates a free electron in the __ band and a corresponding __ in the __ band. a. conduction; electron; valence b. valence; electron; conduction c. conduction; hole; valence d. valence; hole; conduction e. none of the above 15. Conductivity is caused primarily by __ excitation in intrinsic semiconductors. a. momentum b. thermal c. magnetic d. electrical e. none of the above 16. In a semiconductor, electrical conduction occurs by migration of __ and __ under the influence of an electric field. a. electrons; protons b. protons; positrons c. electrons; holes d. protons; holes e. none of the above 17. Electrical conductivity (in a semiconductor) can calculated by the expression sigma = __ + __, where n is the number of electrons/m^3, p is the number of holes/m^3, e is the electron charge, mue is the electron mobility and muh is the hole mobility. a. n/e*mue; p/e*muh b. n*e*mue; p*e*muh c. n*e/mue; p*e/muh d. n+e*mue; p+e*muh e. none of the above 18. The conductivity of pure silicon __ with increasing temperature. a. decreases b. stays the same c. increases d. becomes infinite e. none of the above 19. The conductivity of intrinsic semiconductors __ with increasing temperature. a. decreases b. stays the same c. increases d. becomes infinite e. none of the above 20. The conductivity of metals __ with increasing temperature. a. decreases b. stays the same c. increases d. becomes infinite e. none of the above 21. The number of conduction electron in an intrinsic semiconductor is __ to __, where Egap is the energy bandgap, k is the Boltzmann constant, and T is the temperature of the semiconductor. a. proportional; Egap/kT b. proportional; e^(-Egap/kT) c. inversely proportional; Egap/kT d. inversely proportional; e^(-Egap/kT) e. none of the above 22. The bandgap of Si is __ eV. a. 0.111 b. 111 c. 1.11 d. 1E11 e. none of the above 23. The bandgap of Ge is __ eV. a. 0.0067 b. 0.67 c. 6.7 d. 67 e. none of the above 24. The bandgap of CdS is __ eV. a. 0.24 b. 24 c. 240 d. 2.40 e. none of the above 25. For an intrinsic semiconductor, the number of electrons is __ the number of holes. a. greater than b. equal to c. less than d. infinite compared to e. none of the above 26. In an extrinsic semiconductor, __ create __ electrons or holes. a. thermal excitation; excess b. thermal excitation; a scarcity c. impurities; excess d. impurities; a scarcity e. none of the above 27. In an extrinsic semiconductor, the number of electrons is __ the number of holes. a. equal to b. is not equal to c. infinite compared to d. zero compared to e. none of the above 28. When we dope group V atoms into a group IV matrix, we obtain a __ semiconductor. a. n-type extrinsic b. p-type extrinsic c. n-type intrinsic d. p-type intrinsic e. none of the above 29. For an n-type semiconductor, the number of electrons is __ the number of holes. a. slightly greater than b. slightly lower than c. much lower than d. much greater than e. none of the above 30. If you dope group IV silicon with group V phosphorus, the phosphorus atoms donate excess __ to the semiconductor. a. holes b. electrons c. protons d. neutrons e. none of the above Ch 21 Set 2 1. When we dope group III atoms into a group IV matrix, we obtain a __ semiconductor. a. n-type extrinsic b. p-type extrinsic c. n-type intrinsic d. p-type intrinsic e. none of the above 2. For a p-type semiconductor, the number of electrons is __ the number of holes. a. slightly greater than b. slightly lower than c. much lower than d. much greater than e. none of the above 3. If you dope group IV silicon with group III boron, the boron atoms donate excess __ to the semiconductor. a. holes b. electrons c. protons d. neutrons e. none of the above 4. In an n-type semiconductor, the majority carriers are __. a. holes b. electrons c. protons d. neutrons e. none of the above 5. In an n-type semiconductor, the minority carriers are __. a. holes b. electrons c. protons d. neutrons e. none of the above 6. Group V impurities have __ valence electrons. a. 1 b. 2 c. 3 d. 4 e. 5 7. When a group-V impurity is added to Si (a group-IV matrix), __ valence electrons from the impurity form __ bonds with the nearest Si atom __ electrons. a. 5; covalent; conduction b. 4; covalent; valence c. 5; ionic; valence d. 4; ionic; conduction e. none of the above 8. When a group-V impurity is added to Si (a group-IV matrix), the __ valence electron from the impurity is donated to the __ band if kT > __ MeV. a. fourth; conduction; 44 b. fourth; valence; 440 c. fifth; conduction; 44 d. fifth; valence; 440 e. none of the above 9. Phosphorus substitutional atoms in a silicon are __ ionized at room temperature. a. not b. triply c. fully d. doubly e. none of the above 10. Donor exhaustion occurs in a n-type semiconductor when __ n-type dopant atoms in the material, have __ their extra electrons to the __ band. a. none of the; accepted; conduction b. none of the; donated; valence c. some of the; accepted; valence d. all of the; donated; conduction e. none of the above 11. Boron is a __ dopant in Si and Ge semiconductors. a. n-type b. p-type c. o-type d. b-type e. none of the above 12. Aluminum is a __ dopant in Si and Ge semiconductors. a. n-type b. p-type c. o-type d. b-type e. none of the above 13. Phosphorus is a __ dopant in Si and Ge semiconductors. a. n-type b. p-type c. o-type d. b-type e. none of the above 14. Arsenic is a __ dopant in Si and Ge semiconductors. a. n-type b. p-type c. o-type d. b-type e. none of the above 15. A group-IV p-type semiconductor is semiconductor with intentionally added group __ impurities. a. IV b. III c. II d. V e. none of the above 16. A p-type semiconductor is __ rich. a. positron b. electron c. hole d. excess proton e. none of the above 17. A group III impurity has __ valence electrons. a. 2 b. 3 c. 4 d. 6 e. none of the above 18. When a group-III impurity is added to Si (a group-IV matrix), __ valence electrons from the impurity form __ bonds with the nearest Si atom __ electrons. a. 4; ionic; conduction b. 3; covalent; valence c. 3; ionic; valence d. 4; covalent; conduction e. none of the above 19. When a group-III impurity is added to Si (a group-IV matrix), the __ valence electron from the matrix silicon is donated to the __ band of the impurity atom, if kT > __ MeV. a. third; valence; 450 b. third; conduction; 45 c. fourth; valence; 45 d. fourth; conduction; 450 e. none of the above 20. Boron substitutional atoms in a silicon are __ ionized at room temperature. a. not b. triply c. fully d. doubly e. none of the above 21. Acceptor saturation occurs in a p-type semiconductor when __ p-type dopant atoms have __ an electron from the __ band to create holes. a. none of the; accepted; conduction b. none of the; donated; valence c. all of the; accepted; valence d. all of the; donated; conduction 22. In a p-type semiconductor, the majority carriers are __. a. positron b. electrons c. holes d. excess protons e. none of the above 23. In a p-type semiconductor, the minority carriers are __. a. positron b. electrons c. holes d. excess protons. none of the above 24. For doped silicon, the conductivity __ with increasing doping concentration. a. decreases b. stays the same c. increases d. becomes infinite e. none of the above 25. For n-typed doped silicon, the activation energy is low enough for n-type atoms to donate __ to give the silicon __ band __. a. electrons; conduction; holes b. holes; valence; electrons c. electrons; conduction; electrons d. holes; valence; holes e. none of the above 26. For p-type doped silicon, the activation energy is low enough for p-type atoms to accept __ to give the silicon __ band __. a. electrons; conduction; holes b. holes; valence; electrons c. electrons; valence; holes d. holes; conduction; electrons e. none of the above 27. An extrinsic light doping level is __ /m^3 for phosphorus. a. 1E210 b. 1E2100 c. 1E21000 d. 1E21 e. none of the above 28. At T < __K, the thermal energy is too __ to excite donor electrons. This is called __. a. 600; high; melt-up b. 150; high; melt-up c. 150; low; freeze-out d. 600; low; freeze-out e. none of the above 29. In an extrinsic semiconductor, conduction is extrinsic for temperatures between __ and __. a. 0 K; 150 K b. 150 K; 400 K c. 400 K; 600 K d. 600 K; 1000 K e. none of the above 30. In an extrinsic semiconductor, conduction is __ for temperatures much greater than __. a. extrinsic; 400 K b. extrinsic; 4000 K c. intrinsic; 400 K d. intrinsic; 4000 K e. none of the above ch 22 Set 1 1. The structure of glassy silicate ceramics can be modified by __ modifiers. a. network b. silicate c. ceramic d. glassy e. none of the above 2. The properties of glassy silicate ceramics can be modified by modifying the __ of the materials. a. nuclear levels b. structure c. atomic levels d. properties e. none of the above 3. Flaws can significantly affect the __ of ceramics. a. nuclear levels b. atomic levels c. strength d. conductivity e. none of the above 4. There are different methods for making ceramics __. a. ductile b. strong c. tensile d. stretchy e. none of the above 5. Ceramic materials can be classified as __, __, __, __, __ and __. a. glasses; metals; refractories; abrasives; cements; advanced ceramics b. glasses; clays; metals; abrasives; cements; advanced polymers c. glasses; clays; refractories; abrasives; cements; advanced ceramics d. glasses; clays; refractories; metals; cements; advanced polymers e. none of the above 6. Ceramic glasses can be used for __ applications. a. only optical b. optical and glass container c. only glass container d. stretchy e. none of the above 7. Ceramic clays can be used for __. a. optical applications b. glass containers c. whiteware containers d. polymer bags e. none of the above 8. Ceramic refractories can be used for __ for __ applications. a. magnets; magnetic b. wires; electrically conducting c. bricks; low temperature cycling d. bricks; high temperature e. none of the above 9. Ceramic abrasives are used for __, __ and __ applications. a. glasses; glass containers; glassware b. metal; cutting; polishing c. sandpaper; cutting; polishing d. sandpaper; polymer; polishing e. none of the above 10. Ceramic cements are used for __ applications. a. electrical b. magnetic c. semiconducting d. structural e. none of the above 11. Advanced ceramics are used for __ and __. a. glasses; glass containers b. engine parts; sensors c. whiteware; dinnerware d. sandpaper; abrasives e. none of the above 12. Ceramic silicate glasses are __ silicates (SiO2) containing other __ such as __, __, __ and __. a. crystalline; nitrides; CaN; NaN; K2N; Al2N3 b. crystalline; oxides; CaO; NaO2; K2O; Al2O3 c. non-crystalline; nitrides; CaN; NaN; K2N; Al2N3 d. non-crystalline; oxides; CaO; NaO2; K2O; Al2O3 e. none of the above 13. Container/window glasses contain about __ wt% __ and __ oxides, whose __ are incorporated within the __ network. a. 30; Ca; Na; cations; SiO4 b. 3; Ca; Na; anions; CH4 c. 300; Pb; Sn; cations; SiO4 d. 3000; Fe; Ni; anions; CH4 e. none of the above 14. In soda-lime-silica flat glass, __ and __ are added into the glass to act as __ modifiers. a. Pb; Sn; network b. Fe; Ni; linear c. Ca; Na; network d. Ca; Na; linear e. none of the above 15. In a sodium silicate glass, __ is the glass forming ion, __ is the modifying ion, and the oxygen can be __ and __ atoms. a. sodium; silicon; cation; anion b. silicon; sodium; bridging; nonbridging c. iron; sodium; bridging; nonbridging d. lead; sodium; cation; anion e. none of the above 16. The major types of glasses are __, __, __ and __ glasses. a. lead; iron; silicon; boron b. soda ash; iron; borosilicate; high silica c. soda lime; lead; iron silicate; high silica d. soda ash; lead; borosilicate; high iron e. soda lime; lead; borosilicate; high silica 17. Soda lime glass contains about 11% __ and about 13% __. a. PbO; PbN