1. Electron and Hole Concentrations in Extrinsic Semiconductor
Notes For 25 February
Electron and Hole Concentrations in Extrinsic Semiconductor
For both undoped material and doped material under equilibrium condition 1 1

2. Position of Fermi Energy in Extrinsic Semiconductors
Position of Fermi-level: 2 2

3. Position of Fermi Energy in Extrinsic Semiconductors
Position of Fermi-level: 3 3

4. Variation of Fermi-Energy with Doping Concentration4 4 4

5. Variation of Fermi-Energy with Temperature5 5 5

6. Chapter 5 Carrier Transport Phenomena
Charged carriers in semiconductor: electrons and holes
Carrier transport: movement of electrons and holes
Drift:
charge movement due to electric field
Mechanisms of carrier transport
Diffusion:
charge movement due to density gradient 6 6 6

8. Carrier Drift
Observe that the text uses “e” instead of “q” as a symbol for a unit of charge
Drift current density
Current density due to the holes
Charge density:
Drift velocity of holes
Current density due to the holes
Current density due to the electrons
Charge density:
Drift velocity of electrons
Total drift current density 8 8 8

9. Definition of Carrier Mobility
Drift velocity of holes
Drift velocity of electrons
: mobility of holes
: mobility of electrons
Mobility: relates the average drift velocity of a carrier to the electric field 9 9 9

10. Conductivity Conductivity: Unit: (Ω.m)-1 Resistivity: Unit: (Ω.m)
Intrinsic semiconductor:
N-type semiconductor:
P-type semiconductor: 10 10 10

14. Resistance 14 14 14