1. Copyright © Houghton Mifflin Company. All rights reserved. 16a–1 Figure 16.31: Two-dimensional representations of (a) a quartz crystal and (b) a quartz glass.

2. Copyright © Houghton Mifflin Company. All rights reserved. 16a–2 Figure 16.28: The p orbitals (a) perpendicular to the plane of th carbon ring system in graphite can combine to form (b) an extensive pie bonding network.

3. Copyright © Houghton Mifflin Company. All rights reserved. 16a–3 The Electronic Configuration of a Magnesium Atom nlmlml msms 300+1/2 300-1/2 Mg: (Ne)3s 2 1s 2s 3s 2p 3p Empty 3p orbitals in Mg valence shell

4. Copyright © Houghton Mifflin Company. All rights reserved. 16a–4 Orbital energy levels

5. Copyright © Houghton Mifflin Company. All rights reserved. 16a–5 Figure 16.24: A representation of the energy levels (bands) in a magnesium crystal

6. Copyright © Houghton Mifflin Company. All rights reserved. 16a–6 Figure 16.27: Partial representation of the MO energies in (a) diamond and (b) a typical metal

7. Copyright © Houghton Mifflin Company. All rights reserved. 16a–7 Electron sea model for metals

8. Copyright © Houghton Mifflin Company. All rights reserved. 16a–8 Bonding in Solids Metallic Solids

9. Copyright © Houghton Mifflin Company. All rights reserved. 16a–9 Band structure of Semiconductors

10. Copyright © Houghton Mifflin Company. All rights reserved. 16a–10 Band Diagram: Semiconductor with No Doping At T = 0, lower valence band is filled with electrons and upper conduction band is empty, leading to zero conductivity. –Fermi energy E F is at midpoint of small energy gap (<1 eV) between conduction and valence bands. At T > 0, electrons thermally “excited” from valence to conduction band, leading to measurable conductivity. EFEF ECEC EVEV Conduction band (Partially Filled) Valence band (Partially Empty) T > 0

11. Copyright © Houghton Mifflin Company. All rights reserved. 16a–11 Silicon Crystal Doped with (a) Arsenic and (b) Boron

12. Copyright © Houghton Mifflin Company. All rights reserved. 16a–12 Figure 16.33: Energy-level diagrams for (a) an n-type semiconductor and (b) a p-type semiconductor.

13. Copyright © Houghton Mifflin Company. All rights reserved. 16a–13 pn junction

14. Copyright © Houghton Mifflin Company. All rights reserved. 16a–14 Figure 16.34: The p-n junction involves the contact of a p-type and an n-type semiconductor.

15. Copyright © Houghton Mifflin Company. All rights reserved. 16a–15 PN Junction - 7

16. Copyright © Houghton Mifflin Company. All rights reserved. 16a–16 PN Junction with Applied Potential No current, Barrier LargerCurrent Flows, Barrier Smaller

17. Copyright © Houghton Mifflin Company. All rights reserved. 16a–17 Herbert Kroemer

18. Copyright © Houghton Mifflin Company. All rights reserved. 16a–18

19. Copyright © Houghton Mifflin Company. All rights reserved. 16a–19 Light Amplification by Stimulated Emission Radiation

20. Copyright © Houghton Mifflin Company. All rights reserved. 16a–20 Solar Cells n-typep-type Photons Electron Hole Load p-n Junction under Illumination

21. Copyright © Houghton Mifflin Company. All rights reserved. 16a–21 Solar Panels – Photovoltaic Cells

22. Copyright © Houghton Mifflin Company. All rights reserved. 16a–22 Schematic of a Photovoltaic (solar) cell

23. Copyright © Houghton Mifflin Company. All rights reserved. 16a–23 A schematic of two circuits connected by a transistor.

24. Copyright © Houghton Mifflin Company. All rights reserved. 16a–24 Photolithography to make semiconductor integrated circuits http://britneyspears.ac/physics/fabrication/photolithography.htm

25. Copyright © Houghton Mifflin Company. All rights reserved. 16a–25 (a)-(h) The steps for forming a transistor in a crystal of initially pure silicon.

26. Copyright © Houghton Mifflin Company. All rights reserved. 16a–26 (a)-(h) The steps for forming a transistor in a crystal of initially pure silicon. (cont’d)

27. Copyright © Houghton Mifflin Company. All rights reserved. 16a–27 Semiconductors – key points to remember Band structure: Valence band – gap – conduction band DOPING: Group V  n type, Group III  p type n-p junctions Devices: (LED, laser, transistor, solar cell)

28. Copyright © Houghton Mifflin Company. All rights reserved. 16a–28 Figure 16.24: A representation of the energy levels (bands) in a magnesium crystal

29. Copyright © Houghton Mifflin Company. All rights reserved. 16a–29 Band structure of Semiconductors

30. Copyright © Houghton Mifflin Company. All rights reserved. 16a–30 Semiconductors – key points to remember Band structure: Valence band – gap – conduction band DOPING: Group V  n type, Group III  p type n-p junctions Devices: (LED, laser, transistor, solar cell)

31. Copyright © Houghton Mifflin Company. All rights reserved. 16a–31 Silicon Crystal Doped with (a) Arsenic and (b) Boron

32. Copyright © Houghton Mifflin Company. All rights reserved. 16a–32 Semiconductors – key points to remember Band structure: Valence band – gap – conduction band DOPING: Group V  n type, Group III  p type n-p junctions Devices: (LED, laser, transistor, solar cell)

33. Copyright © Houghton Mifflin Company. All rights reserved. 16a–33 pn junction

34. Copyright © Houghton Mifflin Company. All rights reserved. 16a–34 Semiconductors – key points to remember Band structure: Valence band – gap – conduction band DOPING: Group V  n type, Group III  p type n-p junctions Devices: (LED, laser, transistor, solar cell)

35. Copyright © Houghton Mifflin Company. All rights reserved. 16a–35 C 60 crystals

36. Copyright © Houghton Mifflin Company. All rights reserved. 16a–36 Ionic liquids