ECE 121 Materials Quiz and Answers
1. What is the number of atoms/m3 of silicon given the density of Si is 2.33 g/cm3 and the atomic
weight of Si is 28.1 g/mole. Note that a mole is defined as the quantity of a substance equal to its
molecular weight in grams. In any material, the number of molecules contained in a mole is
Avagadro's number (6.02 × 1023 atoms/mole).: 5 × 1028
2. A value for Áo f 2 × 10-8 ©m• makes the most sense for:: gold
3. Silicon has a native oxide layer when exposed to air. What is the thickness of this layer?: 1.5 nm
4. Silicon is in column (blank) of the periodic chart while donor atoms are lo- cated in column (Blank)
and acceptor atoms are located in column (Blank): IV, V, III
5. Silicon became the preferred semiconductor for electronic devices over Germanium for these
reasons:: 1. devices can operate at higher temperatures
2. the oxide is insoluble in water
6. Crystals are simply an array of repeated unit cells. What Miller indices describe a cube
face?: [100]
7. Silicon crystallizes in the diamond structure which is a face centered cubic with 4 additional
interior atoms. Miller indices identify crystal planes. What crystal plane in silicon has the highest
density of atoms?: [111]
8. The term for point defects in a crystal that describes atoms occupying a space between
occupied crystal sites is (Blank).: interstitials
9. A class 1000 cleanroom is "cleaner" than a class 10 cleanroom (True/False).-
: False
10.The (blank) method is a method for producing a large (Blank) of (blank) silicon from a seed
that is pulled and rotated from molten Si held in a cru- cible: Czochralski, ingot, single crystal
11.The majority carriers in a p-type semiconductor are holes (True/False).: -
True
12.The majority carriers in an n-type semiconductor are holes (True/False).: -
False
13.Silicon has 4 valence electrons that are shared with neighboring atoms by way of an ionic bond
(True/False).: False
14.Doping silicon with a column V element results in:: free electrons that leave behind positively
charged donors
15.Silicon doped with a column III element is considered an extrinsic semi- conductor
(True/False).: True
16. When a p-n junction is formed, majority carriers from each side move to low concentration
areas creating a charge neutral depletion region at the junction. This area contains:: negatively
charged acceptors and positively charged donors
1/
2
1. What is the number of atoms/m3 of silicon given the density of Si is 2.33 g/cm3 and the atomic
weight of Si is 28.1 g/mole. Note that a mole is defined as the quantity of a substance equal to its
molecular weight in grams. In any material, the number of molecules contained in a mole is
Avagadro's number (6.02 × 1023 atoms/mole).: 5 × 1028
2. A value for Áo f 2 × 10-8 ©m• makes the most sense for:: gold
3. Silicon has a native oxide layer when exposed to air. What is the thickness of this layer?: 1.5 nm
4. Silicon is in column (blank) of the periodic chart while donor atoms are lo- cated in column (Blank)
and acceptor atoms are located in column (Blank): IV, V, III
5. Silicon became the preferred semiconductor for electronic devices over Germanium for these
reasons:: 1. devices can operate at higher temperatures
2. the oxide is insoluble in water
6. Crystals are simply an array of repeated unit cells. What Miller indices describe a cube
face?: [100]
7. Silicon crystallizes in the diamond structure which is a face centered cubic with 4 additional
interior atoms. Miller indices identify crystal planes. What crystal plane in silicon has the highest
density of atoms?: [111]
8. The term for point defects in a crystal that describes atoms occupying a space between
occupied crystal sites is (Blank).: interstitials
9. A class 1000 cleanroom is "cleaner" than a class 10 cleanroom (True/False).-
: False
10.The (blank) method is a method for producing a large (Blank) of (blank) silicon from a seed
that is pulled and rotated from molten Si held in a cru- cible: Czochralski, ingot, single crystal
11.The majority carriers in a p-type semiconductor are holes (True/False).: -
True
12.The majority carriers in an n-type semiconductor are holes (True/False).: -
False
13.Silicon has 4 valence electrons that are shared with neighboring atoms by way of an ionic bond
(True/False).: False
14.Doping silicon with a column V element results in:: free electrons that leave behind positively
charged donors
15.Silicon doped with a column III element is considered an extrinsic semi- conductor
(True/False).: True
16. When a p-n junction is formed, majority carriers from each side move to low concentration
areas creating a charge neutral depletion region at the junction. This area contains:: negatively
charged acceptors and positively charged donors
1/
2
