1. ECE 874: Physical Electronics
Prof. Virginia Ayres
Electrical & Computer Engineering
Michigan State University

2. Lecture 18, 30 Oct 12 Chp. 04: Density of states DOS effective mass
Probability that an energy state is occupied
Concentration
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3. Pr. 3.8 http://www.ioffe.ru/SVA/NSM/Semicond/GaP/index.html
<100>
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4. Pr. 3.8
<100>
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5. Pr. 3.8 E2 E1
<100> k2 k1
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6. E2 E1 Pr. 3.8 E = large <100> E = 0 k2 k1 k =
p/alattice constant
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8. E2 E1 Egap Pr. 3.8 Our e- only has up to E2 (eV) <100> E = 0 k2
p/alattice constant
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9. Density of States:
Top energy = our E2
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10. Density of States:
You don’t have all the info you need to calculate this.
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11. Density of States:
Always have an (E, k) pair so this counting will get you a related number:
You do have all the info you need to calculate this.
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12. Density of States: There is a always a connector between E and k:
Pr. 3.8: E = a parabola
Pr. 3.5:
Pr. 3.7:
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13. - Count the number of states N(k) Dk in k-space
Game plan:
- Count the number of states N(k) Dk in k-space
- Convert back to N(E) DE in Energy space. Use the connector.
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14. Streetman & Banerjee
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16. Count the number of states N(k) Dk in k-space
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17. “volume” in in 3D k-space
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19. Convert back to N(E) DE in Energy space. Use the connector.
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22. “volume” in in 2D k-space
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23. Convert back to N(E) DE in Energy space. Use the connector.
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24. VM Ayres, ECE874, F12