This slide set was used to create the MaterialsConcepts YouTube Video "MSE Test Solving Strategies: Electronic Properties". Here is the link to that video:
https://www.youtube.com/watch?v=AtEd_U3MODc
To study the vocab used in this video, visit this site:
http://quizlet.com/24383440/71-electronic-properties-i-conductors-insulators-semiconductors-flash-cards/
This work was supported by NSF Grants #0836041 and #1226325.
2. Test Review Overview
• Summary of Electronic Properties Concepts
• Multiple Choice Test Example Concept Problems
• Calculation Test Example Problems
• Band Structure Schematic Test Example Problems
3. Electronic Properties
Summary
Material Conductivity Increases with:
(or Resistivity Decreases with)
Reasons:
Metals • Decreasing Temperature
• Increasing Grain Size
• Less Cold Work
• Lower Level of Impurities
• Atom vibrations scatter e’s
• Electrons scattered by defects
(impurities, dislocations, and
grain boundaries)
Semiconductors • Increasing Temperature
• Increasing Grain Size
• Adding Impurity atoms
(Doping)
• Thermal energy creates e-h
pairs
• Grain boundaries scatter e’s
• Impurity atoms donate
electrons or electron holes
Insulators • Increasing Temperature • Thermal energy creates e-h
pairs
Note: RESISTIVITY is the inverse of CONDUCTIVITY
6. Doped Semiconductors
p-Type Semiconductor Intrinsic Semiconductor n-Type Semiconductor
Group IV with
Group III Impurity Atoms
Group IV with
No impurities
Group IV with
Group V Impurity Atoms
More holes than electrons
(Majority carriers are
electron holes)
# electrons = # electron holes
(electron-hole pairs)
More electrons than holes
(Majority carriers are
electrons)
7. Concept Question: Example 1
Which of the following terms refer to a Group IV n-type semiconductor?
A) donor
B) exhaustion
C) electron hole majority carrier
D) greater conductivity than p-type with same doping level
E) group III element impurities
8. Concept Question: Example 2
In comparison with intrinsic Si, a B doped Si wafer ( 1025As/m3) has ****
A) greater conductivity
B) a larger energy gap
C) has more n-type carriers
D) has more p-type carriers
E) equal number of p-type and n-type carriers
9. Concept Question: Example 3
Which of the following terms refer to semiconductor devices ****
A) bipolar pnp avalanche diode
B) solar cell
C) rectifier MOSFET
D) dual avalanche diode
E) light emitting diode
10. Concept Question: Example 4
Which of the following will increase the electrical conductivity for Pb?
A) Increasing temperature
B) Decreasing temperature
C) Adding a few % of Cu
D) Increasing the grain size
E) Deforming the metal by cold rolling it
11. Concept Question: Example 5
If the temperature in the room increases from 20C to 50C, conductivity will:
A) increase in a metal like Mg
B) increase in a doped semiconductor like n-type Si
C) increase in an intrinsic semiconductor like Ge
D) decrease in a metal like Cu
E) decrease in a semiconductor like Si
12. Calculations: Example 6
If an intrinsic semiconductor, Eg=.67ev has conductivity of 100 ohm-1 m-1
at 100C, what is the intrinsic carrier concentration if the mobilities are
µe = 0.40 m2 / V-sec and µh = 0.20 m2 / V-sec.
13. Calculations: Example 7
What is the conductivity of a semiconductor if p-type dopant is added
to achieve a concentration of 3.13 x 1021 atoms / m3?
( µe = 0.40 m2 / V-sec, µh = 0.20 m2 / V-sec )
14. Calculations: Example 8
How many grams of boron are required to achieve a concentration
of 3.13 x 1021 atoms / m3 when added to 1 m3 a semiconductor material?
15. Band Structures: Example 9
Draw the band structure for a metal like K (valence = K+1 when ionized), and
a semiconductor like Si and briefly explain the reason for differences in
conductivity for each type of material.
16. Band Structures: Example 10
Using the band gap diagram schematics shown below, show and draw
the charge carriers for intrinsic Si and B doped Si semiconductors.
17. Test Review Wrap-Up
• Summary of Electronic Properties Concepts
• Multiple Choice Test Example Concept Problems
• Calculation Test Example Problems
• Band Structure Schematic Test Example Problems
