MSEASU際際滷s: MSE Test Solving Strategies: Electronic Properties
- 1. MSE Test Solving Strategies: Electronic Properties
- 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 es 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 es Impurity atoms donate electrons or electron holes Insulators Increasing Temperature Thermal energy creates e-h pairs Note: RESISTIVITY is the inverse of CONDUCTIVITY
- 5. Band Structures (Cont.) Semiconductors Insulators
- 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 袖e = 0.40 m2 / V-sec and 袖h = 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? ( 袖e = 0.40 m2 / V-sec, 袖h = 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