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Electron And Hole Equilibrium Concentrations 24 February 2014

Electron And Hole Equilibrium Concentrations 24 February 2014. Return and discuss Quiz 2 Chapter 4 Topics-Two burning questions: What is the density of states in the conduction and valence bands? How do you find an exact position of the Fermi Level?.

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Electron And Hole Equilibrium Concentrations 24 February 2014

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  1. Electron And Hole Equilibrium Concentrations24 February 2014 • Return and discuss Quiz 2 • Chapter 4 Topics-Two burning questions: • What is the density of states in the conduction and valence bands? • How do you find an exact position of the Fermi Level?

  2. Concentration of Electrons at Equilibrium Thermal-equilibrium concentration of electrons (#/cm3) in the conduction band Assume that EF is within the energy bandgap and there is So for energy levels in the conduction band (kT ≈ 25.9 meV for T=300K). So for energy levels in the conduction band Page 87 Text, Equation 3.69

  3. Concentration of Electrons at Equilibrium Define effective density of states in the conduction band 5

  4. Concentration of Holes at Equilibrium Thermal-equilibrium concentration of holes (#/m3) in the conduction band Assume that EF is within the energy bandgap and there is So for energy levels in the conduction band then for energy levels in the conduction band 7

  5. Concentration of Holes at Equilibrium Define effective density of states in the valence band 8

  6. Carrier Concentrations in Intrinsic Semiconductors For an intrinsic semiconductor, the concentration of electrons in the conduction band is equal to the concentration of holes in the valence band is the Fermi-level for the intrinsic semiconductor, i.e., intrinsic Fermi-level For a given semiconductor, at constant temperature, ni isconstant 10

  7. The Intrinsic Fermi-Level position If 12

  8. Fermi-Energy Levels In Extrinsic Semiconductors

  9. Electron and Hole Concentrations in Extrinsic Semiconductor Summary For both undoped material and doped material under equilibrium condition 14

  10. Position of Fermi Energy in Extrinsic Semiconductors Position of Fermi-level: 15

  11. Variation of Fermi-Energy with Doping Concentration 16 16

  12. Variation of Fermi-Energy with Temperature 17 17

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