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
Position of Fermi Energy in Extrinsic Semiconductors Position of Fermi-level: 2 2
Position of Fermi Energy in Extrinsic Semiconductors Position of Fermi-level: 3 3
Variation of Fermi-Energy with Doping Concentration 4 4 4
Variation of Fermi-Energy with Temperature 5 5 5
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
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
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
Conductivity Conductivity: Unit: (Ω.m)-1 Resistivity: Unit: (Ω.m) Intrinsic semiconductor: N-type semiconductor: P-type semiconductor: 10 10 10
Resistance 14 14 14